Full Descriptions

SUMMARY OF

BACKFLOW INCIDENTS

Fourth Edition, December 1995

Published By
PACIFIC NORTHWEST SECTION
AMERICAN WATER WORKS ASSOCIATION

Prepared and Edited by
CROSS CONNECTION CONTROL COMMITTEE
PACIFIC NORTHWEST SECTION
AMERICAN WATER WORKS ASSOCIATION

All publication rights reserved
Copyright 1986, 1992, 1995


This publication can be ordered from PNWS/AWWA
P.0. Box 19581
Portland, Oregon 97280-0581
For questions: call 503/246-5845


Note:
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Forward

There are many backflow incidents which occur that are not reported. This is usually because they are of short duration and are not detected, the customer is not aware they should be reported, or it may not be known to whom they should be reported. Some backflow incidents are detected too late to conclusively determine the cause. Many backflow incident reports are not made public. Understandingly then, the incidents reported in this publication are only a very small number of the incidents that have occurred.

The incidents contained in this publication were obtained from numerous sources. Credit was given on individual reports to the primary source of information, although several sources may have been used to gather information. The incidents were summarized as best as possible from the information at hand. Information on individuals, and company names were normally deleted. Any errors or omissions are inadvertent.

It is the desire of the Pacific Northwest Section, American Water Works Association to bring to the attention of the public, and to water purveyors that do not have a cross connection control program, the risk of contamination of potable water systems posed by cross connection. Providing details of backflow incidents is one way of illustrating the risk. The reader of this publication is encouraged to contribute additional incidents. A backflow incident report form, containing the address for reporting an incident to the PNWS-AWWA Cross Connection Control Committee, is included at the end of this manual.

George Bratton, Chairman
Cross Connection Control Committee
PNWS-AWWA


Acknowledgement

The contribution of those individuals and organizations that have provided incident reports for inclusion in this and previous editions of the Pacific Northwest Section - American Water Works Association SUMMARY OF BACKFLOW INCIDENTS is gratefully acknowledged. Special thanks is given to the following organizations for contributing numerous incident reports, and/or in permitting the use of articles from their publications as a source of information for our summary of a backflow incident:

University of Southern California, Foundation for Cross Connection Control and Hydraulic Research, Los Angeles, California.

Febco, Fresno, CA

Watts Regulators, North Andover, MA through the publication STOP BACKFLOW NEWS

American Backflow Prevention Association, through the publication APBA NEWS

S.F.A Enterprises, through the publication DRINKING WATER AND BACKFLOW PREVENTION

Western Canada Water & Waste Association, through the publication BULLETIN and supporting information from the City of Edmonton, Alberta and City of Winnipeg, Manitoba


Disclaimer

The backflow incidents reported in this manual are provided to give the reader an appreciation of the potential for contamination of a potable water system. It was not the intent of this manual to provide an in-depth account of each incident. Each incident is a summary of information obtained from one or more sources. Source information was accepted as accurately reflecting the backflow incident. When subsequent information on an incident is obtained, the additional information is given as a `postscript' to the original incident report. For any use of the material contained in this manual for purposes other than the one stated above, the reader is responsible for confirming the accuracy of the backflow incident report.


Summary (Short Descriptions)

1923-001 Washington

A typhoid fever epidemic, that resulted in two deaths, was caused by contaminated river water pumped from a lumber mill's auxiliary water supply into the public water mains.

1933-001 Illinois

At the 1933 Worlds Fair, an epidemic of dysentery spread among the visitors, of the eight hundred identified victims, more that forty died. Backsiphonage through "generally defective water and sewerage piping layout" in a hotel was attributed as the cause of the disease outbreak.

1936-001 Vermont

Typhoid bacilli contaminated river water enters city water system through a by-pass maintained solely for fire-fighting purposes, causing the death of a youth.

1938-001 Midwest

University students in a laboratory drank water contaminated with brucella causing severe illness and one death.

1942-001 Kansas

An open valve on a frostproof hydrant permitted sewage from 10 families to enter the water main.

1944-001 Oklahoma

The valve of the main water supply was turned off each night at a school to conserve water causing atmospheric pressure to move waste water into drinking supply.

1947-001 Nebraska

Following a fire, a connecting valve in a pump house was left open allowing river water to enter a school's domestic supply.

1964-001 New York

A pipe to a beverage machine at a golf and country club was connected to the recirculating hot water system containing lye and chromate.

1964-002 Michigan

Backsiphonage from unprotected autopsy table contaminated hospital water.

1965-001 California

Irrigation of a field with undisinfected sewage, in a city whose potable water system is supplied by 12 deep wells, causes at least 246 cases of gastroenteritis.

1967-001 Washington

A cross connection between a gasoline pipeline and the city water system resulted in about 2000 gallons of gasoline entering the water system.

1967-002 New England

A bubbler connected to a fire protection system instead of fresh water line causes seven cases of infectious hepatitis.

1968-001 Washington

A maintenance man ingested water containing sodium dichromate after the contamination of a school's water system by a boiler chemical treatment compound.

1969-001 Arizona

An arsenate based herbicide was backsiphoned into the municipal water system following a water main break.

1969-002 Massachusetts

83 football team members and coaching staff were stricken with infectious hepatitis by drinking water contaminated by a backsiphonage incident.

1969-003 Connecticut

University football team members stricken with infectious hepatitis through irrigation water backsiphonage.

1970-001 Ohio

An open valve at a wine distillery resulted in the backflow of sparkling Burgundy wine into the city water main.

1971-001 Washington

Bacteriological contamination of the community water system would periodically occur following the backflow of stagnant water from an abandoned pressure tank and plumbing system.

1972-001 Washington

The failure to disconnect an air line used to purge exposed water lines during cold weather resulted in air being pumped into the water distribution mains.

1972-002 Arizona

With a loss of water pressure, the pesticide CHLORDANE was backsiphoned through a submerged garden hose into the water distribution system.

1972-003 British Columbia

River water, drawn by an automatic pump, was forced past a check valve into the potable water system of a mill.

1973-001 Washington

Upon the opening of a fire hydrant, the Seattle Fire Department discovered diesel oil in the water; the result of a cross connection between and the hydrant drain and the sewer.

1973-002 New Jersey

A break in a 24-inch water main resulted in CHLORDANE being backsiphoned into the distribution system.

1973-003 Ontario

The water piping in an industrial mall was contaminated through the backflow of a cleaning solvent from an automotive coating shop.

1973-004 Massachusetts

A faulty check valve in a greenhouse allowed fungicide to be injected into city water system.

1974-001 Illinois

Water system contamination resulted from the backsiphonage of the herbicide Balan from a trailer mounted tank being filled by means of a garden hose.

1974-002 Washington

The high rate of flow caused by the activation of a fire deluge system reduced pressure in a domestic water line at the Sea-Tac Airport to below atmospheric causing the backsiphonage of a chemical De-Germ and other pollutants into the potable water system.

1974-003 North Carolina

The backflow of a boiler treatment chemical into the water system caused several children to become ill after consuming contaminated soft drinks at a fast food restaurant.

1974-004 New York

Twenty employees became ill as result of consuming water contaminated with a chromate solution through a cross connection with the building's air conditioning system/make up system.

1974-005 Massachusetts

The backsiphonage of a chromium compound from the chiller water of an air conditioning system contaminated the drinking water system in the auditorium housing the 94th Annual American Water Works Association Conference and Exposition.

1974-006 Massachusetts

Cross connection between dockside potable water and ship's salt water line.

1975-001 Massachusetts

Ethylene glycol from solar heating system enters potable water line.

1975-002 Washington

During the filling of a portable toilet company's tank truck, a solution of soap and formaldehyde was siphoned into a customer's water line service.

1976-001 Washington

The contamination of a small public water supply system was caused by the backsiphonage of the pesticide Endrin from an applicator's tank truck during filling.

1976-002 Tennessee

Water system contamination resulted from the backsiphonage of the insecticide Chlordane following a break in a city water main.

1976-003 Oregon

Water fountains in the State Capitol Building were contaminated with freon gas from a ruptured heat exchanger. The gas after combining with fluoride in the water supply, formed an acid compound that caused a bitter, burning taste.

1976-004 Manitoba

The backsiphonage of a fertilizer occurred when snow clearing operations knocked over two fire hydrants.

1976-005 Texas

A faulty DCVA permitted lake water to be pumped through an irrigation system into the public water supply.

1977-001 Washington

An unprotected cross connection between a closed hot water heating system and the domestic water system resulted in the backflow of Borate-Nitrite from the heating boiler.

1977-002 Ship at Sea

The backflow of a photographic developer solution lead to 544 crewmen on a U.S. Navy vessel developing gastrointestinal illness.

1977-003 Texas

The failure of a control switch permitted the backflow of a scale prevention chemical into a buildings water system.

1977-004 Vermont

A defective check valve on a soft drink dispenser permitted CO2 gas and carbonated water to flow back into copper piping of a hospital water system causing acute gastroenteritis in 36 people.

1978-001 Washington

School's water system contaminated through backsiphonage of septic tank sewage.

1978-002 British Columbia

The contamination of a building's water supply system by high concentration of copper resulted from the backflow of carbon dioxide gas from a beverage machine.

1978-003 British Columbia

The domestic water system in a high rise apartment building was contaminated by the backflow of the corrosion inhibitor Bramco 750 from the apartment's heating boiler.

1978-004 South Carolina

The plumbing system in a church was contaminated by Chlordane backsiphoned through a hose bib following the shut off of the water main in the street.

1979-001 North Dakota

Contamination of a municipal water system by DDT due to backsiphonage from a garden hose type aspirator sprayer.

1979-002 Oregon

Water containing detergent backflowed through a faulty reduced pressure backflow prevention assembly.

1979-003 Idaho

The backsiphonage of "stagnant water" containing high bacterial counts occurred from a fire sprinkler system through a leaking alarm check valve.

1979-004 Washington

The backflow of a cooling solution into a building's water system occurred due to a leak in a cooling coil combined with a faulty control valve.

1979-005 Washington

Contamination resulted when the wash water from a car wash storage tank was pumped into the city water system.

1979-006 Virginia

Water system contamination resulted from the backsiphonage of the insecticide Chlordane following the interruption of water system supply pressure.

1979-007 Arizona

An outbreak of diarrheal illness in campground residents resulted from a cross connection with an irrigation system containing sewage effluent.

1979-008 Texas

Following the shut down of a water main for repairs, steam from a heating boiler emerged from a broken pipe.

1979-009 Iowa

A cross connection of water lines between potable and non-potable water at a meat packing plant caused contamination of $2,000,000 of pork.

1980-001 New Hampshire

A high rise office building's water system was contaminated by the backflow of chemically treated water from a solar heating system.

1980-002 Washington

A leak in a heat exchanger resulted in oil being pumped into the city water distribution system.

1980-003 Alaska

A cross connection aboard a crab processing ship resulted in the backflow of sewage contaminated water that caused about 200 employees to become ill and endangered about $35 million worth of processed king crab.

1980-004 Texas

Following a water main break, it was discovered that the blue colored water had been backsiphoned from a commode tank.

1980-005 Massachusetts

Chromates were pumped into high school potable water system from an unprotected boiler.

1980-006 Washington

A break in a water main resulted in the backsiphonage of 10 to 20 gallons of a detergent solution from a steam cleaning tank.

1981-001 Indiana

Galvanic corrosion between a gas main and a copper water service caused concurrent leaks, hence a cross connection that resulted in contamination of a gas line with water.

1981-002 Virginia

The removal of a damaged backflow preventer lead to salt water being pumped from a shipyard's saltwater fire protection system into the public water system.

1981-003 Pennsylvania

Approximately three hundred residents of a housing development were without water for twenty-seven days following the backsiphonage of the insecticides Chlordane and Heptachlor into their water supply.

1981-004 California

An incorrectly plumbed hydraulic press resulted in the backflow of oil into the city's water main.

1981-005 Texas

An interconnection between the potable water system and a cooling system resulted in the contamination of the water to a pharmacy.

1982-001 Michigan

Malathion contaminated a water distribution system due to backsiphonage through an aspirator type lawn sprayer.

1982-002 Illinois

Ethylene Glycol backsiphoned from an air conditioning system's water holding tank into a group of Dialysis machines contributing to the death of several patients.

1982-003 Oregon

Backflow though an irrigation hose resulted in insect larvae entering a food processing vat.

1982-004 Oregon

A cross connection between the potable water system and a non-potable process water and fire system in a lumber mill was the probable cause of seven confirmed cases of Giardiasis.

1982-005 Massachusetts

The backflow of water containing hexavalent chromium occurred from a chiller in a large manufacturing plant.

1982-006 Eastern U.S.A.

The backflow of propane gas into the city water system occurred when a water connection was left in place following the purging or a propane tank.

1982-007 Washington

A leaking single check valve permitted soapy water from a car wash to be pumped into the city water system.

1982-008 Maine

The backflow of antifreeze from a hot water heating system occurred during the repair of a water main.

1982-009 California

The backflow of carbon dioxide resulted in approximately 200 people at a football game becoming ill.

1982-010 Alaska

Copper laden water enters a carbonated beverage machine. possibly a result of drop in line pressure and backsiphonage of carbonated water into copper pipes.

1983-001 Eastern U.S.A.

A ship's salt water fire system Pumped river water Into a shipyard's water supply system.

1983-002 Washington

A cross connection in a dental office resulted in air being pumped through a hand held aspirator into the building's domestic water system then into the surrounding neighborhood.

1983-003 Maryland

The herbicide Paraquat was siphoned into the town's water distribution system.

1983-004 Manitoba

Following a reduction in water system pressure, a faulty valve permitted the backflow of a caustic chemical solution from a boiler.

1983-005 Texas

The back-siphonage of a chemical in a manufacturing plant resulted in damage to plastic water piping in the plant and to RPBA isolating the plant.

1984-001 Oregon

An interconnection between the potable water lines and the fire supply lines in an Oregon plywood mill lead to several cases of gastrointestinal illness among the mill workers.

1984-002 Oregon

A domestic hot water system was contaminated via a cross connection with a solar hot water heating system.

1984-003 Washington

Air conditioning make up water containing the corrosion inhibitor Nitrate-Borate was pumped into a high rise office building's water system then into the city's distribution system.

1984-004 Washington

The temporary shut down of a water service to a nursing home resulted in the back siphonage of sodium silicate into the building's potable water system.

1984-005 Washington

During the shut down of a water main to repair a valve, the backflow of water from a nursing home's boiler caused burns to a Water Department employee's hands.

1984-006 Kansas

The backflow of boiler water containing a chromate anti-corrosive chemical occurred at an elementary school during the repair of a main break.

1984-007 Oregon

The backflow of hot water from a boiler in a building operated by a diaper service resulted in the melting of the building's 2-inch polyethylene service line.

1984-008 New Mexico

A leaking single check valve on a boiler feed line resulted in a school's potable water system being contaminated with the toxic corrosion inhibitor sodium dichromate.

1984-009 Georgia

Creosote, backsiphoned through a 3/4-inch hose used to prime a pump, contaminated a section of a municipal water system.

1984-010 Alberta

Three leaking check valves at a Light Rapid Transit station allowed polypropylene to enter the water system.

1985-001 Washington

A cross connection with an irrigation system resulted in the pesticide contamination of a well supplying four residences.

1985-002 Washington

The contamination of an office building water system with a cleaning compound was the result of a cross connection to an air conditioning system.

1985-003 Oklahoma

A break in a water line caused the backsiphonage of a mixture of Chlordane, Malathion, Sevin and Diazanon into a portion of the water system service Arpelar, Oklahoma.

1985-004 Washington

A direct connection between a hose bib and a sewer resulted in the backsiphonage of sewer gases/sewage into a single family residence.

1985-005 New York

The backflow of ethylene glycol from an air conditioning make up system into the potable water supply line to a dialysis machine resulted in the death of a patient.

1985-006 California

The pesticide Malathion used by a grain elevator to spray grain as it is loaded into ships, was pumped into the public water system through a faulty check valve.

1985-007 Texas

The backflow of xylene and ethylbenzene from an unknown source resulted in contamination of the water supplied to several customers of a municipal water system.

1985-008 Oregon

Undersized piping appeared to be the cause of back-siphonage of anti-freeze from a fire suppression system.

1985-009 Illinois

Approximately 16,000 persons became ill and two deaths resulted from an "industrial" cross connection that contaminated milk produced from a dairy in Illinois.

1985-010 Florida

A direct connection between a water softener drain line and the sewer may have resulted in the contamination of a home's drinking water.

1985-011 Massachusetts

Car wash water backflows into city water mains.

1985-012 Massachusetts

Chemically treated water from a cooling tower backflowed into potable water supply of a condominium complex.

1985-013 Massachusetts

500-1000 gallons of ethylene glycol and hydrazine treated water backflowed into a hospital domestic water system and city mains.

1986-001 Kansas

Two employees of a grain mill became ill after drinking water contaminated with the pesticide Malathion.

1986-002 British Columbia

The domestic water system in the Provincial Museum was contaminated by the backflow of water from an air conditioning/humidifier unit that contained a corrosion inhibitor.

1986-003 Washington

The residents of Withrow, Washington were without water for four days after herbicide 2,4-D was siphoned into the community's water system.

1986-004 California

Defective operating valves on a lawn sprinkler system allowed surface water to be siphoned into the water distribution system resulting in bacteriological contamination.

1986-005 Oregon

A home owner created a cross connection that allowed the backflow of testing dye from the residence's toilet tank during a high bill investigation.

1986-006 Oregon

A backflow of carbon dioxide from a soda dispenser was allowed by a malfunctioning ball-check valve.

1986-007 Alabama

A water main break caused the backflow of sodium hydroxide into the public water system, resulting in several customers receiving caustic chemical burns.

1986-008 British Columbia

The rupture of a transmission line caused very low or negative pressure throughout a large portion of a municipal water system resulting in the backflow of both bacterial and chemical contaminants.

1986-009 North Carolina

Following a water main break, the pesticides Chlordane and Heptachlor from a tank on a pest control company truck was backsiphoned into the plumbing system of an office building and out into the municipal water system.

1986-010 Manitoba

A faulty check valve on a boiler permitted the backflow of antifreeze into the potable water system.

1987-001 Ontario

Several employees of an electroplating plant were admitted to a hospital after drinking water contaminated with a nickel-based solution siphoned from a plating rinse tank.

1987-002 Oregon

An employee of a plywood mill sustained minor chemical burns while washing his hands following the backflow of an alkaline cleaning compound past two unapproved single check valves into the potable water system.

1987-003 North Dakota

Twenty-nine persons suffered ethylene glycol intoxication after drinking a beverage contaminated as a result of the backflow of anti-freeze from a heating system.

1987-004 Minnesota

The backflow of carbon dioxide from a soft drink machine into the potable water system of a restaurant caused a child to suffer acute copper toxicity.

1987-005 British Columbia

Following the shutdown of a municipal water main to repair a break, a paperboard plant made a temporary connection between the plant's river supplied process water system and domestic water system, permitting the backflow of river water into the public water system.

1987-006 Washington

A large volume of air was injected into the water distribution system when mechanics attempted to clear a frozen water line with compressed air.

1987-007 New Jersey

Nine homes were contaminated with the pesticides Heptachlor, Chlordane and Dursban, following a water main break that allowed the chemicals to be backsiphoned into the public water system through a pest control company's service connection.

1987-008 Idaho

A high water demand caused the herbicide Roneet to be siphoned into a private water system.

1987-009 Oregon

A complaint of dirty, metallic tasting water and air in the lines followed the failure of a ball check valve on a soft drink dispensing machine that utilized a CO2 cylinder.

1987-010 Kansas

The water supply to ten residences and one business were contaminated with the herbicide Lexon DF as a result of backsiphonage caused by a water main break.

1987-011 Florida

Chemically treated water from an air conditioning unit was detected in drinking fountains in two buildings on a university campus.

1987-012 Illinois

The water system in a 550 bed hospital became contaminated when water from the hospital's water cooled air conditioning system "seeped" through a valve linking the two systems.

1987-013 Alberta

A faulty single hard seated check valve on a water line supplying boilers in a high rise building causes hot water to come out of cold water taps.

1987-014 Alberta

Failure of a dual check valve on a soft drink dispenser allowed carbon dioxide to enter the water system.

1987-015 Michigan

Four people at a university residence hall became ill after drinking soda pop from a dispenser. Possible presence of copper-containing sediment in water mix tank.

1987-016 Alberta

A water main break forces chemically treated water into an elementary school's potable water system.

1988-001 Florida

The malfunction of a valve at a paint factory resulted in the backflow of propylene glycol into the factory's potable water system.

1988-002 Ohio

The backflow of a dilute water soluble oil containing toxic chemical additives contaminated the public water main and six house supplied from the main.

1988-003 California

The inappropriate application of a backflow prevention assembly resulted in the backflow of a caustic chemical into an elementary school's potable water system.

1988-004 British Columbia

A naval dockyard's domestic water system was contaminated with saltwater, pumped from a ship's fire protection system into a dockside fire hydrant.

1988-005 Oregon

The backflow of water from a chemically treated boiler occurred as a result of the failure of an unapproved backflow prevention assembly consisting of two check valves.

1988-006 Alaska

The backflow of glycol through a faulty single check valve on a fire sprinkler system resulted in "brown and smelly" water occurring in a high rise building.

1988-007 Georgia

The absence of a backflow preventer on a boiler resulted in the backflow of ethylene glycol into a school's potable water system.

1988-008 Texas

Twelve children suffered from copper poisoning after drinking water contaminated from a soft drink dispensing machine.

1988-009 Missouri

The failure of a backflow prevention assembly resulted in the contamination of a school's drinking water by water from a boiler that contained a chromium based corrosion inhibitor.

1988-010 Alberta

A faulty wafer check valve permitted the backflow of water from a fire sprinkler system into an office building's potable water system.

1988-011 Arizona

An interconnection between an irrigation system and a decorative pond may have resulted in non-potable water being pumped into the public water system.

1988-012 Utah

The apparent failure of a reduced pressure principle assembly resulted in a cleaning solution backflowing into a building water system.

1988-013 Alberta

A water main break caused cleaning solution in a toilet tank to backflow into the residence potable water system.

1988-014 Alberta

Failure of single hard seated check valve allowed water from the heating and chilled water system to enter the potable water system in a shopping mall.

1988-015 Florida

A man died of an insecticide intoxication after drinking water from a bottle filled with contaminated water from a faucet at an airstrip.

1988-016 Arizona

Illegal private wells are suspected as source of contamination of arsenic in the city water supply.

1988-017 Utah

At least five subdivisions have dual water systems for culinary and irrigation water creating possible cross connection health hazards.

1989-001 Oregon

The cross connection of a cooling tower reservoir resulted in the supply of non-potable water to an ice making machine, produce hoses and the employee lunch room in a super market.

1989-002 Washington

About two dozen toilets and urinals in the County Courthouse "exploded" when they were flushed, after an air compressor was connected to the building's water system.

1989-003 Oregon

Eight employees of a high school reported becoming ill after the backflow of ethylene glycol occurred from the school's air conditioning system.

1989-004 Washington

The failure of a single check valve and pressure regulator resulted in the backflow of soapy water from a carpet cleaning truck into a homeowner's hot water tank.

1989-005 Ohio

The backflow of an algae-retarding chemical into the drinking water system of a government office building apparently caused at least 12 illnesses.

1989-006 Washington

A "dirty, black water" complaint alerted the water purveyor to the cross connection of seven water softeners to the sewer line.

1989-007 British Columbia

Following a shutdown of a water main for maintenance, a machine coolant was backsiphoned into the potable water piping in a manufacturing plant.

1989-008 Alberta

The backflow of water through an alarm check valve on a fire system resulted in the contamination of the water supply in a department store.

1989-009 Alberta

The failure of three wafer check valves on a fire system permitted the backflow of yellowish, oily water into the potable water system at a transit station.

1989-010 Alberta

Each time a fire pump was tested, the failure of a wafer check valve on a fire system permitted the backflow of brown water into a print shop.

1989-011 Alberta

Investigation of a water quality complaint revealed that the water piping to a sink and drinking fountain was connected to the fire line hose cabinets.

1989-012 Washington

The shut down of a water main for the installation of a fire hydrant resulted in the backflow of boiler water into the potable water system in a community pool building.

1989-013 Alberta

A backflow incident contaminated the domestic hot water system in a research lab with a growth nutrient for micro-organisms.

1989-014 Alberta

An open bypass valve on a holding tank pump for recycled water allowed "green" water to enter a plastic manufacturing plant's potable water.

1989-015 Missouri

A vintage two story home, split into a duplex, was contaminated with "blue colored" tap water.

1989-016 Arkansas

Propane gas backflows into city water supply causing three buildings to burn, fixtures to explode and several injuries.

1989-017 Utah

Backflow from a fire sprinkler system resulted in propylene glycol entering into a shopping mall's potable water supply.

1990-001 Tennessee

During the summer of 1990, approximately 1,100 guests of a racquet and country club became ill with an intestinal disorder in two mass incidents after consuming the club's contaminated water supplied from an auxiliary well.

1990-002 New York

A hole in a single wall heat exchanger, combined with a bypass pipe around a backflow preventer, resulted in a chemical solvent contaminating a manufacturing building's water supply.

1990-003 Colorado

During a routine check of the heating boiler in a middle school, a valve was left open allowing the boiler water containing the antifreeze ethylene glycol to backflow into the potable water system.

1990-004 Washington

A valve separating the potable water system and an auxiliary water supply to an irrigation system was accidently opened by the fire department during a routine inspection, permitting water from a pond to be pumped into the potable water system at a golf course.

1990-005 Arizona

Drinking water at a police station was contaminated with water from the building's cooling system.

1990-006 Indiana

Six staff members of a middle school reported becoming ill after drinking water containing ethylene glycol that backflowed from the school's cooling system into the potable water system.

1990-007 Washington

Removal of a "one way valve" on a dental chair resulted in the backflow of air into a dental office water lines.

1990-008 Kansas

A malfunctioning solenoid valve on an air compressor in a dental office resulted in the backflow of air into the public water system.

1990-009 New Mexico

An unknown quantity of industrial chemicals is backpressured in the public water supply by a company that transforms wheat and barley into ethanol.

1990-010 Illinois

Excess air pressure causes five toilets to explode in County Courthouse.

1990-011 Utah

Borate/Nitrite accidentally pumped into the potable water system at a retirement home

1991-001 Arkansas

The failure of two single check valves in a series (unapproved backflow preventer) on the service line to a commercial chicken house permitted the backflow, into the public water system, of an antibiotic administered to chickens through the chicken house water system.

1991-002 Washington

The backflow of water from an auxiliary well source resulted in a water main flushing program.

1991-003 Florida

The mistaken connection of the water service for a new house to the reclaimed water distribution line resulted in the customer being supplied with treated wastewater for domestic consumption.

1991-004 Alberta

A single 8-inch check valve on a fire system failed and allowed contamination of the potable water supply to the restrooms in a transit station.

1991-005 Utah

About 100 homes were contaminated after a weed killer was backsiphoned into the public water system.

1991-006 Washington

A boiler cleaning compound was accidentally pumped into a school's water supply instead of the properly protected boiler system.

1991-007 Alberta

The failure to properly flush highly chlorinated water from a new 8-inch pipe before placing it into service resulted in the water system of a building being polluted.

1991-008 Texas

Two check valves on a water chiller allowed bacterial contamination of an Air Force Base water supply.

1991-009 New York

A cross connection between the air conditioning unit and domestic water line at a college results in ethylene glycol in the potable water supply.

1991-010 Missouri

Trichloroethane enters a municipal water supply due to a cross connection at the newspaper office. Disorganized flushing by utility personnel scattered the contaminant throughout the distribution system.

1991-011 Michigan

Parasitical worms were sucked into the drinking water after a water main break.

1992-001 Georgia

Cleaning chemicals, used to remove grease from a commercial kitchen hood, is backsiphoned into the potable water system.

1992-002 Alberta

Employees of a plastic manufacturing company disconnect a vacuum breaker causing backpressure of potassium hydroxide and calsolene oil into the city system.

1992-003 Manitoba

A Seniors Residence experiences intermittent "blue colored" water in taps.

1992-004 Washington

Backsiphonage resulting from a venturi effect caused recurring algae problem in public water distribution system.

1992-005 Washington

A complaint of dirty water at a restaurant reveals CO2 backflowed into city water system.

1993-001 Massachusetts

A restaurant's malfunctioning soda system caused suction within the piping system forcing a chemical agent into the potable water system.

1993-002 New York

A cross connection resulted when a washing machine hose was connected to a hose bib located on both an air conditioner and a potable water system at a blood bank.

1993-003 North Carolina

Chemicals from an x-ray developer were backflowed into the potable water supply of a medical facility.

1993-004 British Columbia

Blue toilet sanitizer water is backsiphoned into potable water system.

1993-005 Oregon

Non FDA approved plastic hose causes bad taste and odor in beverages from a pop machine.

1993-006 Oregon

Water from a drainage pond, used for lawn irrigation, is pumped into potable water supply of a housing development.

1994-001 California

A defective backflow device in the water system of the County Courthouse apparently caused sodium nitrate contamination that sent 19 people to the hospital.

1994-002 New York

An 8-inch reduced pressure principle in the basement of a hospital discharged under backpressure conditions dumping 100,000 gallons of water into the basement.

1994-003 Nebraska

While working on a chiller unit of an air conditioning system at a nursing home, a hole in the coil apparently allowed Freon to enter the circulating water and from there into the city water system.

1994-004 California

The blue tinted water in a pond at an amusement park backflowed into the city water system and causes colored water to flow from homeowners faucets.

1994-005 California

A film company shooting a commercial for television accidentally introduced a chemical into the potable water system.

1994-006 Iowa

A backflow of water from the Capitol Building chilled water system contaminates potable water with Freon.

1994-007 Indiana

Water main break caused a drop in water pressure allowing anti-freeze from an air conditioning unit to backsiphone into the potable water supply.

1994-008 Washington

An Ethylene Glycol cooling system was illegally connected to the domestic water supply at a veterinarian hospital.

1994-009 Ohio

An ice machine connected to a sewer sickened dozens of people attending a convention.

1995-001 Louisiana

The herbicide Paraquat and Atrazine was backsiphoned into the city water system after a water line is cut.

1995-002 Washington

A cross-connection permitted untreated irrigation water to flow into domestic water lines causing 11 cases of giardiasis.

1995-003 Washington

An air compressor connected to the # 1 test cock of a DCVA on a landscaped irrigation system pumped air into the water distribution system.

1995-004 Washington

Pink water was reported in a high rise multipurpose building; the result of a cross connection with a heating/cooling system pump.

 

No. of incident reports: 210


Special Summary

Beverage Dispensing Machines

The number of backflow incidents resulting from the backflow of carbon dioxide from beverage dispensing machines are too numerous to include detailed reports of each incident in this publication. However, some detailed reports of noteworthy incidents are included.

The following special summary of backflow incidents involving beverage dispensing machines is provided to illustrate the frequency of occurrence:

1952, Kokomo, Indiana

Extensive corrosion of a copper cylinder in a manufacturing plant was caused by faulty check valve on a carbonated beverage machine. Twelve persons ill.

1957, Fort Hamilton, New York

Office of the Surgeon General, Department of the Army, indicates faulty check valve on beverage machine results in carbonation in copper water line. Three persons became ill. Reports of carbonation, with no reference to any illness, were also made for First Army Headquarters and a Naval Receiving Station in New York.

1957, Baltimore, Maryland

A four-year-old boy was admitted to the hospital with a complaint of vomiting immediately after consuming a drink from a beverage machine. Laboratory report showed copper salts in gastric washings.

1957, Kansas City, Missouri

A two-year-old girl became ill within 15 minutes of sipping carbonated beverage. Remainder of beverage was taken to laboratory for testing; 35 ppm of copper was found. Rubber check valve leaked overnight. Eight more persons became ill before problem was found.

1957, Los Angeles, California

A small particle which appeared to be a piece of gasket lodged under the single ball, held in place by a spring, of the check valve of a beverage machine. Two persons became ill. Analysis showed 260 ppm copper in the water taken directly from the carbonator, and 110 ppm copper in a drink drawn from beverage machine.

1968, Salt Lake City, Utah

A faulty carbonator check valve caused blue water to the ice machine and bad tasting water at a restaurant.

1977, Burlington, Vermont

Carbon dioxide and carbonated water backflowed into the copper piping in a hospital causing copper poisoning in 38 persons. Copper levels in samples collected from the water system ranged from 7 to 70 ppm.

1977, Wenatchee, Washington

Two persons suffered typical symptoms of copper poisoning after drinking root beer from a beverage machine following the backflow of carbon dioxide into the copper water supply piping.

1978, Vancouver, British Columbia

A building's water supply system was contaminated by high concentrations of copper resulting from a backflow of carbon dioxide from a beverage machine.

1978, Salt Lake City, Utah

Backpressure of carbon dioxide from a beverage dispenser into a restaurant water system.

1979, Mercer Island, Washington

Three persons became ill, reporting symptoms of nausea, diarrhea, abdominal pain and/or headache, after drinking a soft drink that had a "metallic or soapy" taste. A faulty check valve on the soft drink machine had allowed carbon dioxide into the copper water supply line.

1979, Seattle, Washington

Two high school student became ill, showing signs of copper poisoning, after drinking a soft drink from a dispensing machine in a restaurant. Six other similar illnesses were previously reported from the restaurant. The backflow of carbon dioxide from the soft drink dispensing machine was considered the likely cause.

1980, San Antonio, Texas

Carbonated water back-pressured through a faulty check valve into the potable water supply from a soda dispensing machine at a restaurant.

1981, Eugene, Oregon

Backflow of carbon dioxide from beverage equipment in a convenience store resulted from a faulty check valve. No illness reported.

1982, San Antonio, Texas

Check valve failure in soda dispensing equipment resulted in carbonated water being back-pressured into potable water supply at a convenience store.

1982, San Antonio, Texas

Carbonated water from soda dispensing equipment back-pressured through a faulty check valve into the potable water supply at a restaurant.

1982, San Antonio, Texas

Carbonated water from soda dispensing machine back-pressured into the potable water supply through a faulty check valve at a restaurant. Several illnesses reported.

1982, Wenatchee, Washington

Three teenage girls became ill after drinking copper contaminated soft drinks from a drive-in restaurant. Low pressure caused by a water line break in the park across the street from the restaurant resulted in the backflow of carbon dioxide into the restaurant's copper water line.

1982, Monterey Park, California

The backflow of carbon dioxide resulted in approximately 200 people at a football game becoming ill.

1982, Wrangell, Alaska

Two employees of a restaurant became ill with nausea and vomiting after consuming carbonated beverages from a dispensing machine. Copper levels in the beverages sampled were as high as 63 ppm.

1982, San Antonio, Texas

An investigation of a water complaint at a restaurant revealed the check valves (dual check) in a beverage machine had failed, resulting in the backflow of carbonated water. Several employees and customers experienced an upset stomach according to the restaurant owner.

1982, Salt Lake City, Utah (#1)

Backpressure of carbon dioxide from the beverage dispenser in a restaurant.

1982, Salt Lake City, Utah (#2)

Backpressure of carbon dioxide from the beverage dispenser in a hospital cafeteria.

1983, Bellingham, Washington

One person became ill after drinking a contaminated soft drink obtained from a dispensing machine. The soft drink contained 80 ppm of copper.

1983, Winnipeg, Manitoba

In a high school, carbon dioxide from a soft drink machine found its way back into the drinking water through a faulty check valve causing the copper pipe to corrode and turn the water a dark blue color. This incident caused several students to be sickened and school closed for a day.

1984, Camarillo, California

Carbon dioxide from a soft drink machine backflowed into copper piping contaminating the water supply.

1985, Eugene, Oregon

Backflow of carbon dioxide from beverage equipment in a restaurant resulted from a faulty check valve. No illness reported.

1985, Salt Lake City, Utah

Backpressure of carbon dioxide from the beverage dispenser into the potable water system in a post office occurred.

1985, San Antonio, Texas

Carbonated water back-pressured into the potable water supply through a faulty check valve on a soda dispensing machine at a restaurant.

1986, Springfield, Oregon

The backflow of carbon dioxide from a soda dispenser was allowed by a malfunctioning ball-check valve.

1986, San Antonio, Texas

Soda dispensing equipment at a convenience store back-pressured carbonated water into potable water supply though a faulty check valve.

1986, Eugene, Oregon

There was a backflow incident of carbon dioxide through a faulty check valve from the beverage equipment in a convenience store. No illness reported.

1986, Kirkland, Washington

Three persons became ill after drinking carbonated beverages that had a "blue-green" color and a "metallic" taste. The backflow of carbon dioxide was the result of a malfunctioning check valve in the dispensing machine.

1986, Salt Lake City, Utah

Carbonated water backpressured into water supply through a leaking check valve on the soda dispenser at a golf course cafe.

1986, Springfield County, Missouri

The failure of a single check valve on a soft drink dispensing machine at a local fair, resulted in the backflow of water contaminated with 2.7 ppm of copper and 2.2 ppm of zinc. The backflow incident was detected following the report that woman and her two daughters had suffered vomiting and abdominal pain after consuming soft drinks from a food stand.

1987, Crystal, Minnesota

The backflow of carbon dioxide from a soft drink machine into the potable water system of a restaurant caused a child to suffer acute copper toxicity.

1987, British Columbia

Three people became ill in a cafe after drinking soda pop from the vending machine. Water was "bluish" in faucets and vending machine. No malfunction found; suspected that check valve was "stuck" open due to foreign material. Lab test showed 196 ppm of copper and 0.05 ppm of lead.

1987, Michigan

Four people at a university residence hall became ill after drinking soda pop from a dispenser. They reported the pop had an unusual taste and sludge like sediment in their glass. All parts of the machine were in excellent condition. Possible presence of copper-containing sediment in water mix tank was suspected.

1987, Salem, Oregon

There was a backflow incident of carbon dioxide through a faulty stainless steel ball check from the beverage equipment in the food area of a fairground. The water utility received a complaint of brownish, metallic tasting water and air in the lines. No illness reported.

1987, Eugene, Oregon

Carbon dioxide was backflowed from beverage equipment in a convenience store through a faulty check valve. A store clerk complained of "green, bad tasting water". No illness reported.

1987, San Antonio, Texas (#1)

Carbonated water back-pressured into the potable water supply through a faulty check valve on a soda dispensing machine at a restaurant.

1987, San Antonio, Texas (#2)

Carbonated water back-pressured in to the potable water supply through a faulty check valve on a soda dispensing machine at a restaurant.

1987, Kent, Washington

A complaint from a restaurant of a "chemical taste" in the water lead to the discovery of the backflow of carbon dioxide from a beverage system. The standard in-line check valves supplied on the carbonating equipment was replaced with an approved reduced pressure principal backflow assembly.

1987, Summerside, Prince Edward Island

Following a complaint from a restaurant that the soft drinks from their dispensers had "a bitter foam", it was found that a handyman had removed the backflow preventer from the carbonating machine. A period of low water system pressure resulted in the backflow of the contaminated water throughout the building.

1987, San Diego, California

Because of a faulty check valve, several patrons became ill after drinking soda pop from a dispensing machine in a university dining hall. After repair, the dining commons was allowed to resume dispensing beverages. Four days later the water still showed signs of carbonation backflow. It was discovered that the repair person installed re-built check valves into the carbonators.

1987, Sault Ste. Marie, Michigan

Eight people became ill after consuming soda pop from a dispensing machine in a snack bar. Investigation found a large accumulation of particles in the equipment had lodged in the seat of the check valve assembly holding it open. The particles were a result of work performed upstream of water distribution system.

1987, Edmonton, Alberta

Blue stains, air in the water lines, and "caustic" tasting water at a concession stand at a recreational park, revealed a soft drink carbonator's dual check valve had failed allowing carbon dioxide to enter the water system.

1987, Plantation, Florida

A faulty valve operation on a beverage machine at a cinema complex, allowed carbon dioxide to enter the water line. Forty-nine persons became ill after consuming the soda pop.

1988, Edmonton, Alberta

A dual check valve to the soft drink carbonator failed allowing carbon dioxide to enter the water system of a restaurant, causing foul tasting water and large quantities of air in the faucets.

1988, Edmonton, Alberta

A soft drink carbonator's dual check valve failed allowing carbon dioxide to enter the water system of a convenience store.

1988, Bellevue, Washington

The check valves on a soft drink machine malfunctioned, allowing carbon dioxide to backflow into the copper water supply lines. After drinking a soft drink from the machine, one person reported immediately becoming ill with nausea and vomiting, followed by diarrhea.

1988, San Antonio, Texas

Carbonated water back-pressured into the City Water Board distribution system through a faulty check valve in the soda dispensing equipment at a restaurant. An adjacent facility was also affected by the carbonation problem.

1989, San Antonio, Texas (#1)

Carbonated water back-pressured into potable water system through a faulty check valve in soda dispensing equipment in a restaurant.

1989, San Antonio, Texas (#2)

Carbonated water back-pressured into the potable water system through a faulty check valve in soda dispensing equipment in a restaurant.

1989, Garland, Texas

Twelve children suffered from copper poisoning after drinking water contaminated with carbon dioxide from a soft drink dispensing machine.

1989, British Columbia

Several persons became ill with severe and instantaneous vomiting after sipping soda pop or juice in a buffet style restaurant. Both dispensers plus a drinking fountain were served by a single 1/2 inch water service line; there was no sign of backflow prevention valves. All outlets showed high concentrations of copper. High demand on the juice machine caused the carbon dioxide from the pop machine to backflow into the copper holding tank.

1990, Vancouver, Washington

Four people reported becoming nauseous after drinking a beverage from a restaurant's soft drink dispensing machine where the single ball-check valve failed, allowing the backflow of carbon dioxide.

1990, Renton, Washington

Eleven people reported nausea and headache after drinking carbonated beverages from a soft drink dispensing machine where a dual check valve had failed, allowing carbon dioxide to enter the water supply.

1990, Bellevue, Washington

Carbonated water backpressured into the water supply through leaking check valve on a soda dispenser in a restaurant.

1991, San Antonio, Texas

Carbonated water back-pressured into the potable water supply through faulty check valves on soda dispensing equipment in a lounge.

1991, Salt Lake City, Utah

The carbonation unit on a post-mix soft drink machine at a medical center injected carbon dioxide into the potable water system.

1993, Southern Oregon

Owner of a Deli complained of the taste and odor of the water supplying his pop machine. All check valves worked perfectly. Problem was a bad (non FDA approved) flexible plastic hose.

1993, Seattle, Washington

At a large public meeting facility and sports arena, bright blue water was flowing from drinking fountains in the lobby and sinks in the concession area. Several people reported general nausea. The pressure of the carbonation equipment far exceeded pressure in the water main.

1994, Redmond, Oregon

Check valve on a mixer in a beverage machine failed causing bitter tasting water in a restaurant.

 

No. of CO2 incident reports: 64


Full Descriptions


1923-001

DATE OF OCCURRENCE: August, 1923 LOCATION: Everett, Washington

SOURCE OF INFORMATION: G.M. Roscoe vs City of Everett, 10/13/25 PACIFIC REPORTS, Crt. of Appeals, Vol 239

SUMMARY: A typhoid fever epidemic, that resulted in two deaths, was caused by contaminated river water pumped from a lumber mill's auxiliary water supply into the public water mains.

DETAILS:

In April, 1923, the City of Everett installed a new water main to a service area that contained a lumber mill located on the Snohomish river. The mill contained an auxiliary water system supplied by pumped water from the river. The intake for the mill's pump was located a short distance from the point where the city sewers discharged into the river. The auxiliary water system was separated from the public water system by a "series of check valves" to prevent the pollution of the public system. The check valves had a by-pass; the valve on the by-pass was intended to be kept closed.

The public water system normally operated at a higher pressure than the pumped auxiliary system. During the summer months, however, due to the heavy use of water for sprinkling, the pressure in the public system dropped below the pressure of the pumped auxiliary supply.

During the summer of 1923, an epidemic of typhoid fever occurred in Everett. Two persons died from typhoid fever in August of 1923. The investigation of the epidemic revealed that the cause was the contamination of the public water supply from water pumped from the river through the by-pass around the check valves in the mill's service connection. The City of Everett was sued by the families of the deceased. The courts held the city negligent and awarded damages to the plaintiffs. In finding the city negligent, the court cited the following:

- Complaints had been made to city from May continuously until the time of the epidemic, about the smell of the water, its appearance, and that persons were made sick therefrom.

- The city never inspected the valve on the by-pass from the date of installation of the new main to determine if it was closed.

- Any promise made by the mill to remove the by-pass could not relieve the city of responsibility.

- The ease with which the valve could be sealed or the by-pass removed, and the imminent danger from the connection to the auxiliary river supply were strong factors in finding the city negligent.


1933-001

DATE OF OCCURRENCE: 1933

LOCATION: Chicago, Illinois

SOURCE OF INFORMATION: American Weekly, Inc., 1934 courtesy of Bob Stiles

SUMMARY: At the 1933 Worlds Fair, an epidemic of dysentery spread among the visitors, of the eight hundred identified victims, more that forty died. Backsiphonage through "generally defective water and sewerage piping layout" in a hotel was attributed as the cause of the disease outbreak.

DETAILS:

During the first season of the 1933 Chicago Worlds Fair an epidemic of amoebic dysentery spread among visitors, and of the eight hundred victims more than forty died. To trace the disease outbreak, over 16,000 questionnaires were mailed to out-of-town guests who had registered at the hotel during the three months of the summer. As the replies came in, all who reported intestinal symptoms were telephoned or telegraphed to obtain names of the attending physicians, who were notified to watch for amebiasis.

More that twenty law suits in excess of $6,000,000 were filed against the Congress Hotel. The first of these suits, for $600,000, was filed by a doctor and his wife. They became gravely ill with amoebic dysentery which they claim to have contacted while staying at the hotel.

The Entamoeba Histolyica bacteria had spread into the potable water piping in the hotel. The rare disease, as far as the United States was concerned in the 1933, frequently deceived physicians by symptoms which simulate other ailments. It has misled surgeons into operating for appendicitis.

The disease was first thought to have been spread by food handler. However, although all infected food handlers were removed, new cases developed among the guests of the Congress Hotel and of another close by hotel.

The Board of Health report found "old and generally defective water and sewerage piping layouts , potentially, at least, permitting back siphonage of a number of fixtures such as bathtubs and flush-toilets into water lines. An investigation by health authorities revealed that "the pumping plant in Hotel C also supplied water to Hotel A in such a manner that if C's supply became polluted it would also pollute A's ".


1936-001

DATE OF OCCURRENCE: 1936

LOCATION: Winooski, Vermont

SOURCE OF INFORMATION: Supreme Court of Vermont Records, 187 Atl. 808 (1936)

SUMMARY: Typhoid bacilli contaminated river water enters city water system through a by-pass maintained solely for fire-fighting purposes, causing the death of a youth.

DETAILS:

An action was brought by the administrator of the estate of a 17-year-old young man against the defendant city for death allegedly negligently caused by typhoid from typhoid bacilli in river water which contaminated the city water system because the river water got in through a by-pass which was maintained solely for increasing water pressure for fire fighting purposes. The village of Winooski had a water system which was used for domestic and fire purposes, but its pressure was not adequate for fighting extensive fires, and to supplement the village system, a woolen company's supply pipe was equipped with a by-pass with a PIV valve in it. This equipment was so installed that by opening this valve the river water would be forced into the mains of the village system. When this was closed a check valve held back the water from the river and prevented it from entering the village pipes. The purpose was to enable the village to secure added pressure on its mains in case of an unusual fire. Later the city took over the village system and some time later the mill company system was not needed by the city for fire protection, but it was still in use by the mill company and the by-pass and valve remained in place until removed subsequently.

Upon reading the meter of the woolen mill, it was discovered that the meter was running backwards and the valve in the by-pass was left open, which unquestionably established the fact that the river water was passing through the by-pass into the mains carrying city water supplied and used for domestic purposes. The judgment of the lower court entered on the verdict for the plaintiff was affirmed upon appeal.


1938-001

DATE OF OCCURRENCE: 1938

LOCATION: Midwest

SOURCE OF INFORMATION: National Media assembled and summarized by

Watts Regulator Company

SUMMARY: University students in a laboratory drank water contaminated with brucella causing severe illness and one death.

DETAILS:

in 1938, 80 students at a large midwestern university reported remittent fevers, malaise, headache, and anemia. Their symptoms led to a diagnosis of undulant fever (brucellosis). Curiously, only those students who had been working in the cultivation of bacteria in one of the laboratories were affected. Investigation revealed that a hose connected to a faucet in the laboratory, the other end of which was submerged in water containing brucella. A temporary reversal of pressure, possibly the consequence of a demand for water in another part of the system, had drawn the water teeming with brucella into the drinking supply. Of the 80 students affected, one died.


1942-001

DATE OF OCCURRENCE: 1942

LOCATION: Newton, Kansas

SOURCE OF INFORMATION: National Media assembled and summarizes by

Watts Regulator Company

SUMMARY: An open valve on a frostproof hydrant permitted sewage from 10 families to enter the water main.

DETAILS:

In Newton, Kansas, in 1942, one of the town's two water supply mains had been temporarily taken out of service. A house service connection to this main supplied three frostproof hydrants and two frostproof toilets. Some unknown person or persons tried to obtain water from one on the hydrants. When no water flowed, the person departed, leaving the valve open. Later, it was discovered that a neighboring toilet sewer was clogged and that sewage had overflowed into the hydrant box, for 2 days all the sewage from 10 families had been permitted to flow into the water main. When the main was put back into service, there was no attempt to sterilize it and more than 2,500 persons in all parts of town suffered enteric disorders as a result.


1944-001

DATE OF OCCURRENCE: April, 1944

LOCATION: Oklahoma

SOURCE OF INFORMATION: National Media assembled and summarized by

Watts Regulator Company

SUMMARY: The valve of the main water supply was turned off each night at a school to conserve water causing atmospheric pressure to move waste water into drinking supply.

DETAILS:

In April, 1944, after an outbreak of gastroenteritis in an Oklahoma school, it was found that none of the flushometer valve toilets with submerged inlets were provided with vacuum breakers, which prevent atmospheric pressure from forcing waste water into supply lines. Each night, to conserve water and eliminate the possibility that rooms might be flooded if a leak should develop, the custodian turned off the valve at the main supply line. As the pressure in the supply lines was cut off, atmospheric pressure in the toilet bowls moved the waste water up into the drinking supply. Most of the people affected were those who drank from faucets on the first floor of the school; there were progressively fewer cases on the second and third floors, as the atmospheric pressure moved less of the waste water to those heights.


1947-001

DATE OF OCCURRENCE: January, 1947

LOCATION: Milford, Nebraska

SOURCE OF INFORMATION: National Media assembled and summarized by

Watts Regulator Company

SUMMARY: Following a fire, a connecting valve in a pump house was left open allowing river water to enter a school's domestic supply.

DETAILS:

At a school in Milford, Nebraska, the fire lines and hydrants were separate from the domestic water supply, although the two systems were connected through a valve at the pump house. The source of water for the fire system was the river. In January 1947, following a fire, someone negligently opened the connecting valve at the pump house, and river water entered the domestic water supply. About 150 people came down with gastroenteritis.


1964-001

DATE OF OCCURRENCE: 1964

LOCATION: New York

SOURCE OF INFORMATION: National Media assembled and summarized by

Watts Regulator Company

SUMMARY: A pipe to a beverage machine at a golf and country club was connected to the recirculating hot water system containing lye and chromate.

DETAILS:

Eleven caddies experienced nausea, severe vomiting, and abdominal cramps after consuming a "soft drink" at a New York golf club in 1964. The beverage was a commercially prepared mixture of syrup with carbonated water in a vending machine. Investigation revealed that a pipe carrying water into the machine was connected to the recirculating hot water heating system instead of the drinking water system. The day before the incident a lye and chromate solution was added to the hot water system.


1964-002

DATE OF OCCURRENCE: December, 1964

LOCATION: Michigan

SOURCE OF INFORMATION: FCCCHR, University of Southern California

SUMMARY: Backsiphonage from unprotected autopsy table contaminated hospital water.

DETAILS:

In 1964 nurses at a Michigan hospital complained for some time about rusty water coming from one of the hospital drinking fountains before the maintenance department finally checked into the matter. The drinking fountain was located about two doors from the hospital autopsy room. Hospital autopsy tables have a sump to collect cuttings and washing from the autopsy procedure; they are also equipped with a hose-spray unit for washing off cutting, organs, etc. The table at this hospital was not equipped with a hook to hang up the hose-spray, so the pathologist placed the nozzle in the table sump when not in use. The hospital also had severe backsiphonage problems and the autopsy table did not have vacuum breakers installed. Blood and other washing from the cadavers were being sucked into the hospital water supply system and were being encountered by the nurses at the drinking fountain! This is an example of a cross connection in one of the most shocking, revolting and dangerous forms.


1965-001

DATE OF OCCURRENCE: August, 1965

LOCATION: Madera, California

SOURCE OF INFORMATION: Drinking Water & Backflow Protection

March 1995, Volume 12, Number 3

SUMMARY: Irrigation of a field with undisinfected sewage, in a city whose potable water system is supplied by 12 deep wells, causes at least 246 cases of gastroenteritis.

DETAILS:

On the morning of August 13, 1965 the Madera County Health Department learned that Madera physicians were seeing an unusually large number of patients with gastrointestinal complaints. A check of city physicians and pharmacists revealed at least 246 cases of gastroenteritis, heavily concentrated in the southwest part of the city. Diarrhea was the most prominent symptom. Abdominal cramps, nausea, and vomiting were also common. Two children were hospitalized. There were no deaths.

There is considerable evidence that the waterborne epidemic of enteritis was a result of sewage contamination of the city water supply through one of its wells. The direct evidence includes the high coliform count from well No. 14.

Indirect evidence includes the demonstration that water could flow from a sewage irrigated field into well No. 14. Medical data supported the conclusions regarding the contamination.

The waterborne epidemic seems to have occurred as a result of the combination of several circumstances, some of which are unusual:

1. Irrigation of a field with undisinfected sewage.

2. Presence of a gopher hole leading in a particular direction.

3. Connections between the valve excavation and the well pit.

4. Presence in the pit openings to the well casing.

Measures were taken to prevent future recurrences.


1967-001

DATE OF OCCURRENCE: October, 1967

LOCATION: Renton, Washington

SOURCE OF INFORMATION: The Record-Chronicle newspaper

Vol. LXVII No. 42

SUMMARY: A cross connection between a gasoline pipeline and the city water system resulted in about 2000 gallons of gasoline entering the water system.

DETAILS:

About 2000 gallons of gasoline was introduced into the Renton water system when a pipeline company connected a new gasoline pipeline to the water system to pressure test the gasoline line. The Renton fire department flushed a 2-inch water line that ran almost pure gasoline for about 15 minutes. The only injury was to a man that suffered singed hair on his arms then the pan of water he put on his gas stove in his trailer exploded. A nearby lumber company had previously complained of detecting gasoline in their washroom tap water, but when investigators arrived no gasoline could be detected.

It was normal procedure for the pipeline company to use water for hydrostatic testing of gas pipelines. The gas entered the water mains when the pipeline company suffered a mechanical valve failure that allowed gasoline (under higher pressure than the water mains) to backflow into the water system.

The gas pipeline company paid for all the injuries involved and agreed with the city to use a reservoir in future to pump water into gas pipelines instead of directly connecting to a water main.


1967-002

DATE OF OCCURRENCE: 1967

LOCATION: New England

SOURCE OF INFORMATION: National Media assembled and summarized by

Watts Regulator Company

SUMMARY: A bubbler connected to a fire protection system instead of fresh water line causes seven cases of infectious hepatitis.

DETAILS:

A New England town had two separate water systems - one for potable water, the other for fire protection. The fire protection system pumped untreated water directly from the river. In 1967, at an industrial plant in town, workers mistook a fire system line for a fresh water line and connected a bubbler to it. After drinking the water from the bubbler, seven people developed infectious hepatitis and over a hundred were ill with gastroenteritis.


1968-001

DATE OF OCCURRENCE: July, 1968

LOCATION: Spokane County, Washington

SOURCE OF INFORMATION: Byram Enterprises, Spokane, WA

SUMMARY: A maintenance man ingested water containing sodium dichromate after the contamination of a school's water system by a boiler chemical treatment compound.

DETAILS:

A local hospital reported that a maintenance man from a rural school had been brought into emergency complaining of extreme stomach cramps. The man's stomach was pumped. The lab analysis showed that the man has ingested a chromate solution. Further investigation showed that the solution was sodium dichromate, commonly used in boilers for heating buildings.

The school where the maintenance man worked was supplied with water from a well. When the maintenance man disconnected the piping between the pressure tank at the well site and the school building to replace a valve, the building water system was drained toward the well.

The boiler feed line's single cast iron check valve leaked, allowing the backflow of the boiler treatment chemical into the potable water system. When the supply line was returned to service, the boiler treatment chemical was distributed throughout the school's water system.

Upon completing repairs at the well site, and since the day was very warm, the maintenance man immediately returned to the school for a drink of water from a drinking fountain. The maintenance man stated he did not consume a large amount of water, but that the water did have a slight "off taste". Since the school was on summer vacation, no other persons drank the water.

The school plumbing system was thoroughly flushed to remove the chemical.


1969-001

DATE OF OCCURRENCE: September, 1969

LOCATION: Peoria, Arizona

SOURCE OF INFORMATION: City of Glendale, Arizona

SUMMARY: An arsenate based herbicide was backsiphoned into the municipal water system following a water main break.

DETAILS:

On the evening of September 25, 1969, the Water Supply Division received a call from the City of Peoria stating that a portion of their water system had been accidentally contaminated by a poisonous weed killer. A farm workman was filling a weed killer tank utilizing a garden hose from the farmhouse spigot. The water service to the farmhouse is by the City of Peoria's water system. During the filling of the tank the worker left and upon returning noticed that the tank, instead of being full of water and herbicide, was empty. In checking around the area he discovered that a contractor had broken into the water service main directly in front of the farmhouse, draining the main and causing the tank contents to be siphoned into the water system by direct cross connection. He immediately alerted his employer, who in turn called the City of Peoria. They in turn called the State Health Department.

State Health Dept. personnel began immediately sampling the nearby service connections for arsenic levels as the herbicide was a sodium arsenate compound. Meanwhile, the City of Peoria began flushing fire hydrants in the vicinity and warning all users in this section of the system not to consume their water. This was accomplished by the Police and rigidly enforced by loudspeaker trucks. Each resident was warned not to use the water for drinking purposes and to drain his own part of the system by turning on hoses, basins, and other water discharge points.

The Laboratory and the Water Supply Division coordinated their efforts in the collection of the samples and the determination of the various arsenic levels in the system affected by the contaminant. The arsenic level at the farmhouse was determined to be 98 parts per million (ppm), a severe toxic dose for most humans, at the outset of the contamination. After thoroughly flushing this portion of the system it dropped to 0.02 ppm by the next morning. The remainder of the samples in the public water system were less than 0.01 ppm, which is the recommended limit for arsenic. Water supplies containing more than 0.05 ppm of arsenic must be rejected for public use. By 10 a.m. the next day the system had been thoroughly flushed, and all samples indicated the arsenic level had been completely flushed from this portion of the system.


1969-002

DATE OF OCCURRENCE: August, 1969

LOCATION: Worcester, Massachusetts

SOURCE OF INFORMATION: FCCCHR, University of Southern California

Howard D. Hendrickson

SUMMARY: 83 football team members and coaching staff were stricken with infectious hepatitis by drinking water contaminated by a backsiphonage incident.

DETAILS:

A water line, serving a series of sunken sprinkler boxes used for irrigation, was extended to a faucet used by football player for drinking water during practice. Children played on the field and used the irrigation boxes as toilets, 4 of the children had infectious hepatitis.

Early one morning there was a fire in nearby Worcester, fire-fighting pumpers reduced the pressure in the water line to the practice field to below atmospheric, causing backsiphonage.

83 football team members and their coaching staff drank the contaminated water at the faucet and became ill with infectious hepatitis. Nearly every game of the season was cancelled.

Subsequent tests made by flooding the boxes with dyed water and opening fire hydrants in the area below the practice field showed water could flow from the pits to the faucet.


1969-003

DATE OF OCCURRENCE: 1969

LOCATION: New Haven, Connecticut

SOURCE OF INFORMATION: Unknown

SUMMARY: University football team members stricken with infectious hepatitis through irrigation water backsiphonage.

DETAILS:

In 1969 over 50 members of a university football team became ill with infectious hepatitis and their football season was cancelled. Irrigation water had been backsiphoned into the drinking water supply at their locker room through an unprotected cross connection. A main water line repair had drawn water to the atmosphere creating a vacuum or a siphon on the supply line and the irrigation water puddled around the sprinkler heads was drawn back into the potable water system. When water service was resumed, the water contaminated with hepatitis germs was used by the football team for drinking and bathing. The simple installation of a vacuum breaker could have prevented this unfortunate incident.


1970-001

DATE OF OCCURRENCE: December, 1970

LOCATION: Cincinnati, Ohio

SOURCE OF INFORMATION: Environmental Science & Engineering,

November, 1990

SUMMARY: An open valve at a wine distillery resulted in the backflow of sparkling Burgundy wine into the city water main.

DETAILS:

In December of 1970 in a winery in Cincinnati, Ohio the water supply valve was inadvertently left open after flushing out wine-distilling tanks. The result was that during a subsequent fermenting process, sparkling Burgundy backflowed from the vats into the city main and out of the kitchen faucets of nearby homeowners. This typical reversal of flow in water piping caused by the distilling tanks operating at a higher pressure than the city water supply did impair the condition of the water but did not make it dangerous. Indeed, many thought it was the best water they ever tasted.


1971-001

DATE OF OCCURRENCE: December, 1971

LOCATION: Spokane Valley, Washington

SOURCE OF INFORMATION: Byram Enterprises, Spokane, WA

SUMMARY: Bacteriological contamination of the community water system would periodically occur following the backflow of stagnant water from an abandoned pressure tank and plumbing system.

DETAILS:

Bacteriological samples collected from a small grocery store-coffee shop often would show the presence of coliform bacteria. The grocery store-coffee shop was located at the front of a long building. The rear of the building was unoccupied.

Upon investigation, an abandoned well was found in the rear of the building. This well had served seven other premises before the community water system was installed. A connection to the community water system was made at the front of the building. Although the well was abandoned and not attached to the plumbing system, a 500 gallon pressure tank was connected at the rear of the building. The building contained about 400 feet of water piping ranging in size from 1/2-inch to 3-inch. Most of this piping was not in use, hence contained stagnant water.

When the county street flusher truck filled its tank from a nearby fire hydrant, the pressure in the water system dropped to between 30 to 60 psi. This allowed the stagnant water in the pressure tank and piping system in the building containing the grocery store-coffee shop to flow in to the occupied portion of the building and into the community water system. Due to bacteriological regrowth in the stagnant water piping, following a backflow incident, the bacteriological sample collected from the grocery store-coffee shop would show positive with re-samples showing negative.

Abandonment of the pressure tank and all piping downstream of the last utilized plumbing fixture corrected the cross connection.


1972-001

DATE OF OCCURRENCE: November, 1972

LOCATION: Tacoma, Washington

SOURCE OF INFORMATION: City of Tacoma

SUMMARY: The failure to disconnect an air line used to purge exposed water lines during cold weather resulted in air being pumped into the water distribution mains.

DETAILS:

On November 26, 1972, air was pumped into the City of Tacoma water system from a compressor located in the City Transit Shop. An air line used to purge exposed water lines during cold weather had been accidently left on allowing air under 180 psi pressure to enter the city water mains.

As a result of the backflow incident, a foreman and crew spent Sunday afternoon and evening and all day Monday responding to the eleven complaints received from customers related to air being forced into the water mains.

The Transit Shop was ordered to install an approved double check valve assembly on their water service.


1972-002

DATE OF OCCURRENCE: March, 1972

LOCATION: Huachuca City, Arizona

SOURCE OF INFORMATION: Arizona Dept. of Health Services,

City of Glendale, Arizona

SUMMARY: With a loss of water pressure, the pesticide CHLORDANE was backsiphoned through a submerged garden hose into the water distribution system.

DETAILS:

On March 23, 1972, the State Health Dept. received notification from Huachuca City that the city was investigating a complaint of strange taste and odor in the water distribution system. The city thought that the cause was backsiphonage from a drum of pesticides.

Water samples analyzed by the Arizona State Department Laboratory found CHLORDANE pesticide residuals varying from 0.8 to 236 ppb throughout the area.

Upon investigation, a residence was discovered, in the area where the complaints occurred, where pesticides had apparently been mixed regularly in a 30 gallon drum by an employee of an exterminating company. One empty drum with an odor of pesticides was laying on the ground. There were also two faucets with hoses attached, the end of both hoses had a strong odor of pesticides.

On the afternoon of March 21, to install a new water meter on the distribution system, an employee of the water company closed the outlet valve on the pressure tank at the well pump which serves water to the area. The first water quality complaint was received the following day.

The well and pressure tank, and the major portion of the water distribution system are at a lower elevation than the residence where the pesticides were mixed, accounting for the backsiphonage condition.

The only person reporting illness was a woman who drank coke with ice from an ice-making machine in a bar located in the affected area.


1972-003

DATE OF OCCURRENCE: 1972

LOCATION: New Westminster, British Columbia

SOURCE OF INFORMATION: Unknown

SUMMARY: River water, drawn by an automatic pump, was forced past a check valve into the potable water system of a mill.

DETAILS:

A large mill on the Fraser River near New Westminster, British Columbia began experiencing a high rate of absenteeism. The Personnel Manager called on the local health unit to see what might be the cause. The absent employees showed the following symptoms:

1. Stomach Cramps - moderate to severe

2. Diarrhoea - severe, lasting up to six weeks

3. Considerable weight loss (7-20 lbs.)

However, appetites were generally good and employee's families were not affected.

Inspection of the premises revealed that the cafeteria and food dispensing devices were kept clean and sanitary, as were water fountains and washrooms. However, a dual water system was noted. One was connected to the City water supply and provided for washrooms, drinking fountains, automatic food machines and the domestic system generally, as well as for fire hydrants, sprinklers, boilers and various other mill operations. The other was an auxiliary system, connected to that section serving the mill operation. Water for the auxiliary system was drawn from the Fraser River by a pump which was activated whenever the City supply dropped below a set pressure. Also, it was noted that the river inlet was close to the City sewer outfall. There was a check valve below the domestic section and the industrial portion. However, further checking of the system showed that whenever the automatic pump drew water from the river, it was forcing the water past the check valve on the domestic side of the system. No lives were lost but the episode was certainly expensive in terms of days off work and lost production.


1973-001

DATE OF OCCURRENCE: March, 1973

LOCATION: Seattle, Washington

SOURCE OF INFORMATION: Seattle Water Department

SUMMARY: Upon the opening of a fire hydrant, the Seattle Fire Department discovered diesel oil in the water; the result of a cross connection between and the hydrant drain and the sewer.

DETAILS:

On Saturday, March 24, 1973 the Seattle Water Department received a report that the fire department had operated a fire hydrant and "gasoline" had come out of the port. Upon inspection, there was oil around the fire hydrant (it turned out to be diesel oil) and in the street, but the water coming out of the fire hydrant cleared after a few minutes. It was theorized that the diesel oil had entered the barrel of the hydrant through the underground drain on the hydrant.

On the following Monday, the odor oil was found again in the water from the fire hydrant. The hydrant was dug up and a drain line was found leading to the sewer. An inspection of the area found diesel oil in a nearby service station and the operator reported that diesel oil had been dumped into the sewer recently.


1973-002

DATE OF OCCURRENCE: May, 1973

LOCATION: Marlboro Township, New Jersey

SOURCE OF INFORMATION: Watts Regulator Company "Stop Backflow"

SUMMARY: A break in a 24-inch water main resulted in CHLORDANE being backsiphoned into the distribution system.

DETAILS:

An exterminating contractor created an illegal cross connection by diluting a quantity of the highly toxic insecticide, CHLORDANE, by means of a submerged garden hose into a drum. A break in a 24-inch water main occurred during this operation, caused a negative pressure in the distribution system resulting in the backsiphonage of the contents of the drum, through the house service connection and into the distribution system.

Although extensive flushing of the water main was undertaken by the water authority, the velocity provided by the standard fire hydrant ports was insufficient to properly flush out CHLORDANE from the large main. The required velocity was achieved by attaching a fire pumper truck to a 4-inch port on the hydrant.


1973-003

DATE OF OCCURRENCE: October, 1973

LOCATION: Metro Toronto, Ontario

SOURCE OF INFORMATION: Watts Regulator Company "Stop Backflow"

SUMMARY: The water piping in an industrial mall was contaminated through the backflow of a cleaning solvent from an automotive coating shop.

DETAILS:

On October 25, 1973, a backflow incident was reported in an automobile coating shop located in an industrial mall. Cars are driven into the shop for the application of undercoating and preventative coating in trunks, under hoods, door panels, etc., to prevent corrosion. The mall was only partially filled with tenants; the undercoating shop located in number 11, and the next occupied unit being number 21, leaving 9 unoccupied units in between.

In the pre-cleaning operation, hot and cold water was fed to pump operating at approximately 75 psi. The discharge side of the pump connected to a gun type spray nozzle. A hose was then connected from the pump into a solvent tank that supplied the solvent to the spray gun.

On October 25, the pump was left on between cycles, allowing the pump pressure of 75 psi to overcome the city water main pressure of 50 psi, causing the cleaning solvent to backflow into the potable water supply piping in the mall. A tenant in unit number 21, the next occupied unit, reported a bad taste in the water, leading to a discovery of the cross connection.

In order to clean the water piping of the contaminant, it was necessary to drain the lines, after which they were steam cleaned.


1973-004

DATE OF OCCURRENCE: 1973

LOCATION: Woburn, Massachusetts

SOURCE OF INFORMATION: Howard D. Hendrickson

SUMMARY: A faulty check valve in a greenhouse allowed fungicide to be injected into city water system.

DETAILS:

Due to a cross connection between a pressurized chemical application system and a potable water line and a mechanical failure of an unapproved single check valve, an undetermined volume of a fungicide was injected into the city water distribution system. City water pressure - 60 psi, Chemical application system pressure - 300 psi.

Numerous complaints were received concerning odorous drinking water from residents in the area.


1974-001

DATE OF OCCURRENCE: June, 1974

LOCATION: Soldiers Grove, Illinois

SOURCE OF INFORMATION: "Water & Sewage Works", November, 1974

SUMMARY: Water system contamination resulted from the backsiphonage of the herbicide Balan from a trailer mounted tank being filled by means of a garden hose.

DETAILS:

On June 11, 1974 the Village of Soldiers Grove, Illinois reported that their water system had been contaminated by the herbicide Balan. A fire hydrant was being replaced at a major intersection in the village. Because no valve was provided in the hydrant lead and valving of the water main was inadequate, it was necessary to close off the reservoir and drain the entire distribution system. The herbicide entered the distribution system just 200 feet east of the hydrant being replaced.

The herbicide had been syphoned out of a 300 gallon tank mounted on a trailer. At the time of the water system shutdown, water was being added to the tank by means of a garden hose, with the end submerged in the liquid. Six and one half gallons of herbicide had been added to the tank.

The herbicide Balan is practically non-toxic, and at least 2 lbs. of the undiluted herbicide would have to be ingested by a 200 lb. man to cause death.

The water system was thoroughly flushed and chlorinated before being returned to service.


1974-002

DATE OF OCCURRENCE: July, 1974

LOCATION: Seattle, Washington

SOURCE OF INFORMATION: Seattle Water Department

SUMMARY: The high rate of flow caused by the activation of a fire deluge system reduced pressure in a domestic water line at the Sea-Tac Airport to below atmospheric causing the backsiphonage of a chemical De-Germ and other pollutants into the potable water system.

DETAILS:

On July 18, 1974 an engineer with Sea-Tac Airport informed the Seattle Water Department that a backflow incident had occurred at one of the airline buildings and that a chemical, De-Germ, was introduced into the potable water supply. Two units of the airline building's fire deluge system had activated, causing the chemical and possible other pollutants to enter the domestic water system at the facility.

Two pumps at the airport water pumping station had activated, causing a peak of 195 psi in the airline hanger facility. About 15 minutes elapsed before the airport fire department had secured both the fire and domestic water supplies. A 2-inch water line to an irrigation system at the airport broke on or about the same time that emergency pumps were activated. When the water service was restored, blue colored water was observed coming from the drinking fountains.

The hanger facility has one 2000 gallon capacity storage tank containing the blue colored chemical De-Germ, used to sanitize and flush toilets in aircraft. A 1 1/4-inch RPBD was installed as a result of an earlier backflow incident in this area. It was found that a domestic 3/4-inch cold water line was directly connected to the storage tank lines, by-passing this RPBD.

When the deluge system was activated and excessive demand was placed on the supply system, reducing pressure to less than atmospheric. The chemical and possibly other pollutants were backsiphoned into the domestic water system. When the emergency pumps were activated, the chemical was spread to other areas of the airline hanger.


1974-003

DATE OF OCCURRENCE: December 1974

LOCATION: North Carolina

SOURCE OF INFORMATION: Watts Regulator Company "Stop Backflow"

SUMMARY: The backflow of a boiler treatment chemical into the water system caused several children to become ill after consuming contaminated soft drinks at a fast food restaurant.

DETAILS:

On December 7, 1974 in a moderate size city in North Carolina, a fast food restaurant received complaints of a bitter taste in the soft drinks they were selling. Over 300 people were served soft drinks during the period in question.

Syrups were changed several times but to no avail. The manager, realizing the principle ingredient was water, drew a glass of water from the nearby tap. It was found to be discolored with a strong chemical taste. The local water department was notified and an investigation was immediately started.

The water department traced the problem to a chemical in the water and determined that the particular chemical was used to treat boiler water in a fertilizer plant, located one half mile away from the restaurant. Investigation at the fertilizer plant revealed that a check valve on the supply line to the boiler was leaking and allowed the chemicals in the boiler to backflow into the water main in the street that supplied both the fertilizer plant and the restaurant.

Complaints of children becoming ill as a result of drinking the beverages at the restaurant have been received with threats of lawsuits.


1974-004

DATE OF OCCURRENCE: September, 1974

LOCATION: New York City, New York

SOURCE OF INFORMATION: Watts Regulator Company "Stop Backflow"

SUMMARY: Twenty employees became ill as result of consuming water contaminated with a chromate solution through a cross connection with the building's air conditioning system make up system.

DETAILS:

On September 21, 1974, trouble developed in the 5th and 6th floor air conditioning system located in a 32 story office building. The building was equipped with an air conditioning system located in the roof, however, the 5th & 6th floors had an independent system.

To repair a compressor, the service company temporarily connected the 5th and 6th floor system to the building's air conditioning system. Following repair of the compressor on September 22, a maintenance man from the service company connected a hose from a threaded faucet on the 5th floor to the 5th and 6th floor air conditioning system to obtain make-up water. However, the building's air conditioning system remained hooked into the 5th and 6th floor air conditioning system. Since the building's air conditioning system pressure was higher than the potable water system pressure on the 5th and 6th floors, water from the air conditioning system containing chromates flowed through the temporary hose connection into the potable water system.

Twenty employees in the office building became ill after drinking the chromate contaminated water.


1974-005

DATE OF OCCURRENCE: June, 1974

LOCATION: Boston, Massachusetts

SOURCE OF INFORMATION: Watts Regulator Company "Stop Backflow"

SUMMARY: The backsiphonage of a chromium compound from the chiller water of an air conditioning system contaminated the drinking water system in the auditorium housing the 94th Annual American Water Works Association Conference and Exposition.

DETAILS:

Tuesday, June 18, 1974, was a hot humid day for the thousands of registrants at Boston's Hynes Memorial Auditorium for the 94th Annual American Water Works Conference and Exposition.

Murmurs of "turn up the air conditioning" were soon followed by "check the air conditioning" as thousands of people noticed a yellow hue to the drinking water. A chromium compound was added to the chilled water system by means of manual shut-off valve. It was later determined that this shut-off valve was inadvertently left open. A reverse flow condition occurred and resulted in "yellow water" being distributed to drinking fountains, soda fountains and coffee makers in the auditorium.


1974-006

DATE OF OCCURRENCE: 1974

LOCATION: Boston, Massachusetts

SOURCE OF INFORMATION: Howard D. Hendrickson

SUMMARY: Cross connection between dockside potable water and ship's salt water line.

DETAILS:

An unprotected cross connection between dockside potable water line and a salt water line aboard a ship caused Boston Harbor water to be pumped into the city water line. Normal city pressure - 60-75 psi, Salt water pump pressure - 70-80 psi.

1975-001

DATE OF OCCURRENCE: 1975

LOCATION: Chelmsford, Massachusetts

SOURCE OF INFORMATION: Howard D. Hendrickson

SUMMARY: Ethylene glycol from solar heating system enters potable water line.

DETAILS:

A potable water line was contaminated with ethylene glycol due to an unprotected cross connection between the solar heating system and the potable water line in a small commercial building. A complaint of distasteful water was registered by an employee.


1975-002

DATE OF OCCURRENCE: June, 1975

LOCATION: Tacoma, Washington

SOURCE OF INFORMATION: City of Tacoma

SUMMARY: During the filling of a portable toilet company's tank truck, a solution of soap and formaldehyde was siphoned into a customer's water line service.

DETAILS:

On June 16, 1975, a truck driver employed by a portable toilet company attempted to fill a tank on his service truck from a standpipe connection on a domestic water service line while a City of Tacoma Water Division crew was working on the service connection. The water was turned off at the service connection to permit the city crew to cut the 3-inch service pipe to install a new water meter. The truck driver submerged a hose in his tank containing a soap and formaldehyde solution, then turned on the hose bib, thus creating a backsiphonage situation which resulted in the contents of the tank being siphoned into the service line.

No one was reported to have consumed any of the contaminant.

The water customer was ordered to install vacuum breakers on all hose connections within the property. The portable toilet company was instructed to install an approved air gap on the fill connection their tank truck.


1976-001

DATE OF OCCURRENCE: November, 1976

LOCATION: Wenatchee, Washington

SOURCE OF INFORMATION: American Water Works Association

"Opflow", May, 1977

SUMMARY: The contamination of a small public water supply system was caused by the backsiphonage of the pesticide Endrin from an applicator's tank truck during filling.

DETAILS:

In November, 1976, approximately 300 gallons of liquid containing 1.2 lbs of the pesticide Endrin was backsiphoned from a pesticide applicator's truck into a small public water system service to 21 residents at East Monitor near Wenatchee, Washington. Endrin is a very toxic chlorinated hydrocarbon which is applied to orchards in the late fall for the control of mice. The lethal dose (LD 50) for the compound is 5 mg (dosage) per kg (body weight).

The incident occurred when, by coincidence, three applicators were filling their trucks from three separate hydrants on a pipeline connecting the system's well to a storage tank. The tank was located about 1/2 mile away at an elevation of nearly 200 feet above the well. The withdrawal of water to fill the trucks at the lower elevation created a negative pressure in the high end of the pipeline and the contents of the truck at that location were siphoned into the system.

The system does not have anyone in charge on a full-time basis. Consequently, the contamination problem was not detected and brought to the attention of health officials until two days after the incident took place. During that time, several families drank and bathed in the contaminated water. Fortunately, the chemical was greatly diluted in its passage through the storage tank and no illnesses were reported.

When the State was notified, the system was ordered shut down, water consumers were appraised of the situation and a sampling program was initiated. The initial samples showed 130 ppb of Endrin in the water. It was necessary to drain and scrub the reservoir and continually flush the system for more than a week before the contaminant was reduced to negligible levels and the system could be placed back into operation.


1976-002

DATE OF OCCURRENCE: March, 1976

LOCATION: Chattanooga, Tennessee

SOURCE OF INFORMATION: "Morbidity and Mortality Weekly Report"

SUMMARY: Water system contamination resulted from the backsiphonage of the insecticide Chlordane following a break in a city water main.

DETAILS:

On March 24, 1976 several residences in Chattanooga, TN noticed that their tap water had suddenly turned white and smelled of insecticide. By the following day it was established that a 3 block area was affected and the water supply was promptly cut off by the water purveyor. Samples of the water taken on the evening of March 24, revealed Chlordane as the contaminant in concentration up to 1200 parts per million.

A house-to-house survey conducted on March 26 & 27, reached 45 of the 49 affected households. Of the 112 persons questioned, 17 said they had drunk the suspect water, another 15 had casual contact through washing, bathing or brushing teeth. Four persons gave a history of probable Chlordane toxicity; that is gastrointestinal symptoms such as nausea, abdominal pain, in addition to neurological involvement such as dizziness, blurred vision, irritability, headache, paresthesia, muscle weakness, or twitching. Nine others had gastrointestinal symptoms alone. One of the suspected cases developed a fever of 102 F. No deaths occurred.

Results of the quantitative analysis for Chlordane in the water focused attention on a section of one affected street as the possible source of contamination. A strong smell of Chlordane came from the fountain of a house there, and soil samples from around the house were found to contain Chlordane in concentrations greater than 1,000 ppm. Chlordane had been used at the house on March 24, for extermination of termites. The concentrated Chlordane solution had been diluted with tap water approximately 90 minutes before Chlordane was detected downstream in the water system. The exact mode of entry of the insecticide into the water supply is not clear. The most likely explanation is that the siphonage of Chlordane occurred during the process of diluting the insecticide when the hose from the faucet dipped below the level of the concentrated Chlordane. Several water mains had been broken the preceding week by contractors, causing variable water pressure in the system. The Chattanooga Water Department later reported that all traces of Chlordane could not be flushed from the system, the 3 blocks of contaminated water mains were replaced and 47 homes vacated. The total cost for main replacement and payment of damages exceeded $1,000,000.


1976-003

DATE OF OCCURRENCE: March, 1976

LOCATION: Salem, Oregon

SOURCE OF INFORMATION: City of Salem

SUMMARY: Water fountains in the State Capitol Building were contaminated with freon gas from a ruptured heat exchanger. The gas after combining with fluoride in the water supply, formed an acid compound that caused a bitter, burning taste.

DETAILS:

On the evening of March 9, 1976 in the State Capitol Building at Salem, Oregon, two maintenance workers drank water from a drinking fountain and reported a bitter taste to security guards.

About 8:30 a.m. the next morning, one maintenance worker sampled the water by taking a drink from a fountain. The worker still felt a burning sensation in his mouth at 10:30 a.m. The fountains in the building were shut down and "taped off" to prevent anyone from drinking from them.

The suspected contaminant was freon gas that entered the potable water system through a rupture in a heat exchanger of a chilling unit. This was confirmed later in the afternoon when a refrigeration repairman arrived to test and repair the heat exchanger.

Freon gas when mixed with water containing fluoride creates a type of acid, thus explaining the burning sensation experienced by the maintenance personnel.

Maintenance personnel removed the heat exchanger from the system, completely drained the water system, including the holding tank on the top floor, then flushed the system.


1976-004

DATE OF OCCURRENCE: 1976

LOCATION: Winnipeg, Manitoba

SOURCE OF INFORMATION: Western Canada Water & Waste Association

SUMMARY: The backsiphonage of a fertilizer occurred when snow clearing operations knocked over two fire hydrants.

DETAILS:

In Winnipeg, Manitoba, in 1976, as a result of snow clearing operations, two fire hydrants within a one block area were knocked over. The result was that through backsiphonage a blue colored liquid fertilizer from a nearby florist operation entered the water supply. Numerous consumer complaints were received. Since the contamination was colored, luckily no one ingested the water.


1976-005

DATE OF OCCURRENCE: April, 1976

LOCATION: San Antonio, Texas

SOURCE OF INFORMATION: City of San Antonio, Texas

SUMMARY: A faulty DCVA permitted lake water to be pumped through an irrigation system into the public water supply.

DETAILS:

On March 16, 1976 the San Antonio Water Board received a call from an employee of a claims center, stating that there was possibility that water from a private lake located on the grounds had been pumped through the lawn sprinkler system into the center's domestic line, then into the public water main.

An investigation revealed that no chlorine was present in the claims center domestic water supply, and bacteriological samples taken of the water were positive for total coliform. At the same time, the public water system had a chlorine residual of 0.75 mg/L, which could indicate that no lake water had entered the public water system. However, a check of water meter readings showed approximately 103,000 cu. ft. of water went through the meter in the reverse direction.

A 3-inch double check valve assembly was installed on the supply to the lawn irrigation system from the center's domestic line. The DCVA was not tested at the time of the installation in 1974 or at any time thereafter.

The irrigation service with the DCVA was removed, leaving the irrigation system to be fed solely by the auxiliary supply.


1977-001

DATE OF OCCURRENCE: February, 1977

LOCATION: Seattle, Washington

SOURCE OF INFORMATION: Department of Public Health

Seattle and King County

SUMMARY: An unprotected cross connection between a closed hot water heating system and the domestic water system resulted in the backflow of Borate-Nitrite from the heating boiler.

DETAILS:

On February 15, 1977 a hospital in Seattle, Washington reported "red" water. Upon investigation, the problem was determined to be a cross connection between the closed hot water heating system and the cold water make-up supply line. No backflow prevention device was provided on the hot water heating boiler. A PRV apparently failed, forcing water treated with Borate-Nitrite (for corrosion protection) back into the potable water system.

The Borate-Nitrite solution in the hot water heating system is mixed 1:1000. The water in the lavatory above the cross connection had approximately 175 parts per million Borate-Nitrite. The water in the fresh water make up line had approximately 3450 ppm Borate-Nitrite. The color of the water was pink and fuschia respectively.

The Poison Center was contacted to determine the toxicity level of Borate-Nitrite and to determine what effect, if any, the material would have on the accidental consumer. The levels detected in the lavatory hand basin were low enough that only persons who were acutely sensitive to the material would have any reaction. However, the strongly contaminated water would have caused skin reactions and immediate vomiting. There were no further incidents reported in the hospital and no cases of illness noted from ingesting the Borate-Nitrite.

A RPBD was installed on the water make-up line to the boiler.


1977-002

DATE OF OCCURRENCE: July, 1977

LOCATION: Ship at sea

SOURCE OF INFORMATION: "Morbidity and Mortality Weekly Report"

Volume 27, Number 28, July 14, 1978

SUMMARY: The backflow of a photographic developer solution lead to 544 crewmen on a U.S. Navy vessel developing gastrointestinal illness.

DETAILS:

Between July 21 and July 31, 1977, 544 crewmen aboard a large U.S. Navy vessel developed gastrointestinal disease. The illness was characterized by the acute onset of nausea, vomiting, abdominal cramps, and diarrhea generally resolving within 12 to 36 hours. Stool and vomitus culture from patients as well as cultures of water and various foods failed to yield any bacterial pathogens.

On the morning of July 28, when reporting for their required morning roll call, 301 men from four units with the high attack rates wee interviewed. Fifty-five of these individuals met the definition of the case, i.e., vomiting during the last seven days, leaving 246 controls. Interview responses indicated that cases were significantly more likely to have drunk water while the ship was at sea, implicating the ship's water system.

On July 19, two days prior to the onset of the outbreak, a chilled drinking water system to the forward part of the ship was used for the first time in over a year. Because the time relationship implicated this water system, it was shut down July 28. Within the next 24 hours, there was a reduction in the number of cases.

Subsequently, it was learned that the chilled water system supplied water to automatic photo-developing machines on the ship. A makeshift cross connection in the form of a rubber hose was detected leading to the ship's potable water system from a 40 gallon tank used to mix photographic developer solution that contained hydroquinone.


1977-003

DATE OF OCCURRENCE: July, 1977

LOCATION: San Antonio, Texas

SOURCE OF INFORMATION: City of San Antonio, Texas

SUMMARY: The failure of a control switch permitted the backflow of a scale prevention chemical into a buildings water system.

DETAILS:

On July 11, 1977, the water quality division received a call from a building manager complaining about having green water throughout his four story building.

An investigation revealed a cross connection between a scale prevention chemical and the potable water supply existed within the building. The chemical was being pumped into the potable water supply due to a failure of the control switch which stuck in the "on" position and continuously pumped the chemical over the weekend in the reverse direction from that intended. No backflow preventer was installed on the cross connection.

The owner was ordered to install a reduced pressure principle assembly at the point of the cross connection and also at the water meter on the service to the building.


1977-004

DATE OF OCCURRENCE: March, 1977

LOCATION: Burlington, Vermont

SOURCE OF INFORMATION: Morbidity and Mortality Weekly Report

July 8, 1977

SUMMARY: A defective check valve on a soft drink dispenser permitted CO2 gas and carbonated water to flow back into copper piping of a hospital water system causing acute gastroenteritis in 36 people.

DETAILS:

Three employees at a Vermont hospital became ill with nausea and vomiting on the afternoon of March 28, 1977, within 5 minutes of consuming a carbonated soft drink in the hospital coffee shop. A survey of hospital employees revealed 46 additional individuals who had onset of gastrointestinal symptoms during the afternoon or evening of the same day, of all those reporting illness, 36 had consumed soft drinks dispensed from the beverage machine.

Samples of water and ice produced in an ice machine indicated pH levels below 5.4 and the presence of a blue precipitate. After re-suspension of the precipitate in the laboratory, the copper levels in the water and ice samples ranged from 7-70 mg/l. (E.P.A. recommends levels of copper no higher than 1.0 mg/l).

The carbonated beverages were dispensed from a machine that was supplied by carbonated water produced in a system adjacent to the machine. Carbon dioxide gas from pressurized tanks was mixed with water to form the carbonated water used in the soft drink dispenser. A defective check valve had permitted the co2 gas and carbonated water to flow back into the copper piping of the hospital water system. Leaching of the copper from the pipes resulted in high levels of copper in the water supplied to the beverage and ice machines and to the tap.


1978-001

DATE OF OCCURRENCE: May, 1978

LOCATION: Pierce County, Washington

SOURCE OF INFORMATION: Dept. of Social and Health Services

State of Washington

SUMMARY: School's water system contaminated through backsiphonage of septic tank sewage.

DETAILS:

On May 4, 1978 the Artondale School reported approximately 200 out of 608 children from the school were absent. At the close of school the day before only 15 were absent. The cause of the absenteeism appeared to be a gastrointestinal illness.

The Washington State Epidemiologist reported that the bulk of the clinical illness was most likely caused by the Norwalk agent virus. Illness spread through household contacts of students and faculty with a secondary attack rate of approximately 32%. The illness, in total, affected over 75% of the students and teachers at the Artondale School.

Drinking water at the school was the vehicle by which the etiologic virus was transmitted. The water showed evidence of fecal contamination.


1978-002

DATE OF OCCURRENCE: January, 1978

LOCATION: Vancouver, British Columbia

SOURCE OF INFORMATION: Vancouver Water Department

SUMMARY: The contamination of a building's water supply system by high concentration of copper resulted from the backflow of carbon dioxide gas from a beverage machine.

DETAILS:

On January 18, 1978 employees of a theater reported that the water in the building had a blue color and a strong "mineral" taste. The problem occurred intermittently and a sample of the water taken that afternoon revealed nothing unusual. However, a sample taken and analyzed the next day was found to contain 245 parts per million of copper. Drinking water standards suggest a limit of 1.0 ppm of copper.

A cross connection inspection found a pressure regulator on a carbon dioxide cylinder used at the beverage bar had malfunctioned, resulting in a large amount of gas entering the domestic water system. The standard ball check valve installed on this type of beverage dispenser was ineffective in preventing backflow.

The carbon dioxide formed carbonic acid, which caused rapid internal corrosion of the copper water piping in the theater.

Although copper is not considered to be a cumulative systematic poison such as lead or mercury, a high concentration in the water supply may cause nausea or discomfort, and in a very limited number of people, an allergic reaction.


1978-003

DATE OF OCCURRENCE: March 10,1978

LOCATION: Vancouver, British Columbia

SOURCE OF INFORMATION: Vancouver Water Department

SUMMARY: The domestic water system in a high rise apartment building was contaminated by the backflow of the corrosion inhibitor Bramco 750 from the apartment's heating boiler.

DETAILS:

On March 10, 1978 the residents of a high rise apartment building in Vancouver's West End reported that their water had a blue color and a bitter "rubbery" taste. Water Department staff responding to the complaint determined that the "blue" water was confined to the apartment building.

An inspection of the apartment revealed that the single soft seated check valve on the boiler feed line was leaking. The expansion of the water (steam) when heated caused a backflow of the water in the boiler past the leaking single check valve into the domestic water system. The analysis of the tap water revealed that the water contained a corrosion inhibitor, Bramco 750, that was presently being used in the apartment's boiler for the hot water heating system. Only one of the three components of Bramco 750 is toxic when used full strength. With the dilution of the corrosion inhibitor after mixing with the potable water, the consumption of it would not be toxic.

The Water Department issued an order to replace the single check valve with an approved reduced pressure principle backflow prevention device. The apartment's domestic water system was thoroughly flushed to remove all traces of the corrosion inhibitor.


1978-004

DATE OF OCCURRENCE: August, 1978

LOCATION: South Carolina

SOURCE OF INFORMATION: Watts Regulator Company "Stop Backflow"

SUMMARY: The plumbing system in a church was contaminated by Chlordane backsiphoned through a hose bib following the shut off of the water main in the street.

DETAILS:

In August, 1978 an exterminator was treating a church located in a small town in South Carolina for termite and pest control. The highly toxic insecticide, Chlordane, was being mixed with water in buckets, and garden hoses were left submerged in the buckets during the mixing process.

At the same time, water department personnel came by to disconnect the parsonage water line from the church to install a separate meter for the parsonage. In the process, the water main was valved off in the area of the church. The church is located on a steep hill, and, as the remaining water in the lines was used by other residents in the area, the church was among the first places to experience a negative pressure. The Chlordane was quickly siphoned back into the water lines within the church.

The exterminators finished their work and left, unaware that a backsiphonage had occurred. That same night, Vacation Bible School began, and as the mothers were mixing kool-aid in the kitchen, the Chlordane laced water was used. Due to the very strong Chlordane odor being prevalent throughout the church, detecting the odor in the water was difficult. However, some of the adults did detect the bad taste and odor in the water just as the children had been served the kool-aid. The children were warned immediately and the remaining kool-aid was taken away for disposal.

Approximately a dozen children and three adults experienced dizziness and nausea. None of the affected required hospitalization or sought medical attention.

The plumbing in the church was flushed repeatedly and chlorinated. Liquid dishwashing detergent was flushed through the system in an effort to remove the Chlordane from the water pipes. Yet, some months later the whole church had to be re-plumbed in order to get rid of the lingering Chlordane which clung to the walls of the pipes and continued to affect the water adversely.


1979-001

DATE OF OCCURRENCE: March 1979

LOCATION: Kulm, North Dakota

SOURCE OF INFORMATION: American Water Works Association

"Opflow", May 1979

SUMMARY: Contamination of a municipal water system by DDT due to backsiphonage from a garden hose type aspirator sprayer.

DETAILS:

During the summer of 1979 the residents of Kulm, North Dakota complained that their water had an iodine-like taste. The water left a burning sensation on the lips and throat for 10 to 15 minutes. Residents reported both the burning sensation and minor stomach disorders. Both the southeast and north side of town was affected. The mayor notified the state health department. The National Guard was called in to provide an alternate supply of water.

The distribution system was flushed eight times over a period of three days to remove the contamination. Laboratory analysis confirmed the presence of DDT at both locations. A trace amount of DDT was found in the samples taken after repeated flushing of the system, however, none of the levels were high enough to be toxic to humans.

Backflow prevention and cross connection control in Kulm was reviewed. During the survey, two Kulm residents were found filling sprayers containing herbicide with their garden hoses. The ends of the hoses were immersed in the herbicide water and the hoses had no backflow preventer. If a negative pressure developed in the water system, the herbicide could have been drawn into the water system. Apparently this is how the DDT was introduced. Subsequent demands on the system spread the DDT contamination. The ultimate source of the DDT was never found. The identification of the banned substance only adds to complicate the matter. The sampling done by the state health department was done after the fact, hence the levels of DDT could have been even higher at the initial time of contamination.


1979-002

DATE OF OCCURRENCE: September, 1979

LOCATION: Portland, Oregon

SOURCE OF INFORMATION: Portland Water Bureau

SUMMARY: Water containing detergent backflowed through a faulty reduced pressure backflow prevention assembly.

DETAILS:

On September 18, 1979 a concrete plant at the foot of S.E. Ivon Street reported foamy water in their plant. Two water samples taken from within the plant by a Portland Water Bureau water quality inspector confirmed the foaming agent. Samples were taken from three fire hydrants in the area; at two of the hydrants foamy water was found. Water Bureau crews were dispatched to flush water mains in the affected area.

A dairy in the area was suspected as the source of the contaminant since the backflow of a similar agent occurred there in 1970 before the installation of backflow prevention devices in the dairy's service connections. A check of the dairy's detergent wash station found an indication of a possible backflow from the detergent pump lines.

Both of the dairy's reduced pressure principle backflow prevention devices were tested and both found to be in poor condition with a 4-inch device completely failing the test (both check valves and the relief valve). The Water Bureau records showed that the dairy's devices were installed by a contractor in 1971; one 4-inch and one 3-inch. In their last annual performance test in February, 1979 both devices met the minimum test specifications, i.e. relief valve opened at 2.0 psi.

Complete repair kits were installed on both devices, replacing discs, gaskets and all worn parts.


1979-003

DATE OF OCCURRENCE: June 1979

LOCATION: Meridian, Idaho

SOURCE OF INFORMATION: Department of Health and Welfare,

State of Idaho

SUMMARY: The backsiphonage of "stagnant water" containing high bacterial counts occurred from a fire sprinkler system through a leaking alarm check valve.

DETAILS:

On June 18, 1979 the residents of the City of Meridian, Idaho reported their water supply had an odor and taste of onions. During this period, the city was routinely flushing fire hydrants throughout the area involved. As with the complaints, the odor would occur but a consistent pattern could not be determined. The city's water system is supplied by four wells and a 500,000 storage tank which rides on the system. The wells have an alternate pumping schedule and the water system is looped. This arrangement had a contributing affect on the odor occurrence.

By isolating portions of the water system, and conducting a premise by premise inspection, the source of the contamination was narrowed to one area containing a supermarket, car wash and a church printing firm. The nearest fire hydrant was flushed and the odor became very strong. The final inspection revealed that the alarm check valve on the fire sprinkler system in the supermarket was leaking. When the city water pressure was reduced during hydrant flushing, the alarm check valve clapper would leak, but the clapper would not open enough to set off the alarm. When the service was turned off to the supermarket , the odor and taste problem did not occur during hydrant flushing. Water samples taken from the sprinkler system identified Clonothrix fusa and Zoogleora ramigera bacteria in sufficient concentration that would cause the onion taste and odor problem.


1979-004

DATE OF OCCURRENCE: October, 1979

LOCATION: Seattle, Washington

SOURCE OF INFORMATION: Seattle Water Department

SUMMARY: The backflow of a cooling solution into a building's water system occurred due to a leak in a cooling coil combined with a faulty control valve.

DETAILS:

On October 29, 1979 the Seattle Water Department received a phone call from a customer concerning pink water flowing from a drinking fountain in their machine shop. By the time the Seattle Water Quality Inspector arrived, employees of the company had found the cause of the pink water; a heat exchanger cooling solution (similar to hydraulic fluid) was being forced back into the potable water system that supplied the heat exchanger. The gate valve on the city service pipe was closed immediately and the circulating pump shut off. The pump was operating at 160 psi against a city water main pressure of 70 to 80 psi. Samples of the "pink" water were taken, the building plumbing system flushed thoroughly, and the city water main serving the building flushed as well. Apparently none of the cooling solution had been pumped back into the city supply main.

An inspection of the plant found that the cooling solution used at a milling machine is monitored by a temperature controlled valve on the discharge side of the heat exchanger. When the solution temperature rises, this valve opens and allows city water to flow through the coils in the heat exchanger to cool the solution. The city water is discharged to waste.

The backflow condition occurred with the concurrent failure of two of the system components. First, the cooling coil carrying city water developed a leak. This normally would not itself have posed a problem, since it would discharge to waste. However, the temperature controlled valve on the discharge line also malfunctioned and stuck in the closed position, thereby creating a situation in which the 160 psi pump was forcing the cooling solution back through the coil into the water supply.

A reduced pressure principle backflow prevention device was ordered placed on the water supply line to the heat exchanger.

In the past, heat exchangers or other devices with cooling coils were not cited by seattle as a cross connection as long as the discharge was air gapped at a drain receptacle. The primary concern was sewerage backing up and submerging the discharge line and permitting backsiphonage under a negative pressure condition.


1979-005

DATE OF OCCURRENCE: February, 1979

LOCATION: Seattle, Washington

SOURCE OF INFORMATION: Seattle Water Department

SUMMARY: Contamination resulted when the wash water from a car wash storage tank was pumped into the city water system.

DETAILS:

On February 12, 1979 several residents of the Greenwood District of Seattle, Washington reported soapy water coming from their taps. The investigation by the Seattle Water Department found that the soapy water came from a car wash on Aurora Avenue North.

On February 10, a pump broke down at the car wash. This was a high pressure pump which takes its suction from the tanks containing reclaimed wash & rinse water, and pumps (recycles) it into the wash cycle of the car wash. This cycle is not designed to be connected to the car wash potable water supply.

After the pump broke down, the piping in the rinse cycle which operates with city water pressure was connected to the wash cycle piping by means of a two inch hose. This arrangement allowed the car wash to remain in operation during pumps repairs.

On February 12, the owner came to the car wash and examined the pump. The pump was repaired almost immediately and turned on. The two inch hose (cross connection) remained connected between the rinse and wash cycle piping. The pump forced the contents of the two reclaim tanks (850 gallons) into the 12-inch water main on Aurora Avenue North through the car wash service connection.

Sometime later, an employee went into the car wash's restroom and noticed brown soapy water in the toilet bowl after it flushed. The cross connection was immediately realized and the two inch hose removed.

The contamination was confined to an eight block area. The water mains were flushed and chlorinated by the Seattle Water Department.

A reduced pressure principle backflow prevention device was ordered installed on the water service pipe to provide premise isolation.


1979-006

DATE OF OCCURRENCE: October, 1979

LOCATION: Roanoke, Virginia

SOURCE OF INFORMATION: Watts Regulator Company "Stop Backflow"

SUMMARY: Water system contamination resulted from the backsiphonage of the insecticide Chlordane following the interruption of water system supply pressure.

DETAILS:

On October 12, 1979 the residents along the 4900 block of Autumn Lane complained that their water looked milky, felt greasy, foamed and smelled like "a combination of kerosene and Black Flag pesticide". Approximately three gallons of Chlordane, a highly toxic insecticide, had been backsiphoned into the city water system.

The contamination occurred while water department personnel were repairing a water main. At the same time an exterminator was treating a nearby home with Chlordane for termite control. The workmen for the exterminating company left one end of the hose connected to an outside hose tap and left the other in a barrel of diluted insecticide. During the water service interruption, the solution was backsiphoned into the house plumbing and then into the city water main. The homes in the effected area, because of the hilly terrain, were particularly susceptible to backsiphonage.

The water department undertook an extensive program of flushing water mains. The insecticide, however, adhered to the inside of the pipes. Tests of water samples taken six days after the contamination showed Chlordane levels five times greater than considered safe.

The water department tapped into the water main at two points along the street to continue flushing operations. For several days residents either carried water to their homes from two 400 gallon water tanks the city put up on a vacant lot in the area, or traveled to homes of friends or relatives to shower and eat meals.

The contamination affected homes in the 4700 to 4900 block of Autumn Lane. As can be expected, a lawsuit was initiated. In 1985 the lawsuit was settled in the plaintiff's favor with an award of $13,000,000.


1979-007

DATE OF OCCURRENCE: June, 1979

LOCATION: Sandpoint, Arizona

SOURCE OF INFORMATION: Arizona Department of Health Services

City of Glendale, AZ

SUMMARY: An outbreak of diarrheal illness in campground residents resulted from a cross connection with an irrigation system containing sewage effluent.

DETAILS:

Between June and September, 1979 six groups of California residents and one group of Arizona residents reported experiencing a diarrheal illness during and after visiting a marina and campground at a state park on the Colorado River. The diarrheal illness was characterized by watery diarrhea, abdominal cramps, weight loss, nausea, chills, headache, vomiting and fever (G. 100 deg. F).

The only risk factor associated with illness was drinking water from one's campsite faucet. Forty of the 76 persons who drank campsite water became ill as compared with 17 of the 86 persons who denied drinking the water. The attack rate increased with the amount of water consumed. Illness was not associated with water from other sources, water skiing, swimming, food from the campground store, or ice.

Evaluation of the water system in September revealed a cross connection between a water pipe serving the west side of the campground where the campers reported becoming ill, and an irrigation pipe containing sewage effluent.


1979-008

DATE OF OCCURRENCE: February, 1979

LOCATION: San Antonio, Texas

SOURCE OF INFORMATION: City of San Antonio, Texas

SUMMARY: Following the shut down of a water main for repairs, steam from a heating boiler emerged from a broken pipe.

DETAILS:

On February 13, 1979 the water board dispatched a crew to repair a water main break. When the water main was shut down for repairs, with the subsequent loss of water pressure, a steady flow of steam emerged from the pipe.

The steam entered the water system from a chemical injected steam boiler located in a nearby building.

The owners of the building were required to install an approved air gap or approved reduced pressure principle assembly on the service to the building.


1979-009

DATE OF OCCURRENCE: October, 1979

LOCATION: Marshalltown, Iowa

SOURCE OF INFORMATION: Environmental Science & Engineering

November, 1990

SUMMARY: A cross connection of water lines between potable and non-potable water at a meat packing plant caused contamination of $2,000,000 of pork.

DETAILS:

In October 1979 at a meat packing plant in Marshalltown, Iowa, $2,000,000 worth of pork was contaminated. The meat became contaminated when the plant employees sprayed contaminated water on hog carcasses and cuttings during the normal cleaning process. Food safety and quality service officials have concluded that there was a cross connection of water lines between potable and non-potable water, causing sewage water from the kill floor and water used to deodorize rendering operations to get into the potable water line.


1980-001

DATE OF OCCURRENCE: March, 1980

LOCATION: Manchester, New Hampshire

SOURCE OF INFORMATION: Watts Regulator Company "Stop Backflow"

SUMMARY: A high rise office building's water system was contaminated by the backflow of chemically treated water from a solar heating system.

DETAILS:

On March 1, 1980 a large fire occurred two blocks away from a seven story office building in downtown Manchester, N.H. On March 2, the maintenance crew of an office building arrived to perform the weekly cleaning, and, after drinking the water from the drinking fountains, noticed a strong bitter taste. They notified the Manchester Water Company which promptly initiated an extensive investigation. Samples of the water were taken from the fixtures within the building, from neighboring buildings, and from the water mains in the street. Preliminary analysis of the samples disclosed that the contaminants found were not typical of the usual water main contaminants associated with fire line disturbances.

The seven story office building housed one of the newest solar heating systems in the northeastern area of the U.S. and accompanying it was a very complex plumbing and piping system. A cross connection control inspection traced the water line to determine the source of the contaminate. A potable supply line was located that fed the make-up water to a 10,000 gallon hot water storage tank that was used for heat storage for the solar heating system. Corrosion inhibiting chemicals were added to the storage tank. The line did not contain a backflow prevention device.

Due to thermal expansion, the storage tank pressure could increase above the city supply pressure. Normally backflow would not occur because a booster pump in the main supply line would keep the supply pressure to the storage tank greater than the highest tank pressure. Unfortunately, at the time of the fire, the pressure in the city mains was depleted to an unusually low point and the low pressure cut-off switches simultaneously shut off the booster pumps in the building. This combination gave the boiler water, together with its chemical contaminants, time to travel into the potable water system within the building. When pressure was reestablished in the city mains and the booster pumps resumed operation, contaminated water was delivered throughout the entire building.


1980-002

DATE OF OCCURRENCE: October, 1980

LOCATION: Tacoma, Washington

SOURCE OF INFORMATION: Tacoma Water Department

SUMMARY: A leak in a heat exchanger resulted in oil being pumped into the city water distribution system.

DETAILS:

On October 2, 1980 The City of Tacoma Water Department received several complaints of oil in the water in the 1800 block of North Bristol Street. It was determined that the oil was automatic transmission fluid coming from the variable speed pump at the Westgate Pumping Station at North 21st and Pearl Streets.

Water was being taken from the discharge side of the pump through a heat exchanger to cool the transmission fluid for the variable speed pump drive, then put back into the suction side of the pump. The transmission fluid line inside the heat exchanger developed a leak which allowed the fluid to mix with the water and be pumped into the water distribution system.

The pump station was shut down until the heat exchanger could be replaced. The cross connection was protected by the installation of a double check valve assembly on the supply to the heat exchanger and piping the discharge to the sewer through an air gap.

Fire hydrants in the area were flushed to clear the oil from the distribution system.


1980-003

DATE OF OCCURRENCE: September, 1980

LOCATION: Unalaska, Alaska

SOURCE OF INFORMATION: Seattle Post Intelligencer,

October 18, 1980

SUMMARY: A cross connection aboard a crab processing ship resulted in the backflow of sewage contaminated water that caused about 200 employees to become ill and endangered about $35 million worth of processed king crab.

DETAILS:

A preliminary report filed by the Alaska State epidemiologist stated that the water supply of a crab processing barge converted from a World War II Liberty ship had become contaminated on September 22 or 23, 1980 and that workers on the barge suffered attacks of vomiting and diarrhea until about September 26. The source of the contamination was the ship's sewage system.

The processing barge draws its water supply from a reservoir which also supplies the town of Unalaska and some 30 fish processing and canning plants in the area. The reservoir's filters became clogged, reducing water pressure in the system. The crab processing barge turned on its own pumps to boost its pressure. The ship's pumps "somehow" created a vacuum in the system and sucked raw sewage back into the water supply.


1980-004

DATE OF OCCURRENCE: November 19, 1980

LOCATION: San Antonio, Texas

SOURCE OF INFORMATION: City of San Antonio, Texas

SUMMARY: Following a water main break, it was discovered that the blue colored water had been backsiphoned from a commode tank.

DETAILS:

On November 19, 1980 the Water Quality Division was notified that blue water was emerging from the main break. Upon investigation, very dark blue-green water was found in a large quantity.

It was determined that the blue water was back-siphoned from the commode tank located at a nearby residence. The customer at this address had a bottle (inverted) of a Blue-Boy type additive installed in the tank. The commode type filler valve was a fluid master without a vacuum breaker installed. The customer was notified of the hazards involved with such an installation.


1980-005

DATE OF OCCURRENCE: 1980

LOCATION: Boston, Massachusetts

SOURCE OF INFORMATION: Howard D. Hendrickson

SUMMARY: Chromates were pumped into high school potable water system from an unprotected boiler.

DETAILS:

Chromates from a boiler were pumped into the potable water system of a regional high school. Fortunately, the custodian noticed yellow colored water in the drinking fountain. School was closed for five days to flush and chlorinate water lines and to install a backflow preventer.

1980-006

DATE OF OCCURRENCE: August, 1980

LOCATION: Clallam County, Washington

SOURCE OF INFORMATION: Washington Department of Health

SUMMARY: A break in a water main resulted in the backsiphonage of 10 to 20 gallons of a detergent solution from a steam cleaning tank.

DETAILS:

In August, 1980 a water main break on the supply line to a reservoir in a small water system broke. The water users exhausted the stored water supply, there was no longer a positive pressure in the water system. Between 10 and 20 gallons of the detergent K-90 in a steam cleaner tank at a trucking company was backsiphoned into the potable water system. When water pressure was restored, the workers at the trucking company noticed the color of the water was green.

The water system was flushed and chlorinated.

Approximately 1,000 people were affected by the cross connection incident.


1981-001

DATE OF OCCURRENCE: 1981

LOCATION: South Bend, Indiana

SOURCE OF INFORMATION: Indiana Section-AWWA "News Leaks"

SUMMARY: Galvanic corrosion between a gas main and a copper water service caused concurrent leaks, hence a cross connection that resulted in contamination of a gas line with water.

DETAILS:

The natural gas company in South Bend, Indiana was puzzled and frustrated for several days by the presence of water in their gas lines. In the residential area where it occurred there were sputtering gas appliances, frozen gas regulators and homes without heat.

A 3/4-inch copper water service to a house was found to be touching a 2-inch steel gas main. Exactly at the touch point a 1/8-inch hole had developed in each line and a tight, solid cross connection was formed. Since the water was at a higher pressure than the gas, the gas line was "contaminated" with water.

Both lines were installed at the three foot depth, although specifications called for five feet on the water service. Records show the gas main was installed in 1951 and the water service in 1952.


1981-002

DATE OF OCCURRENCE: January, 1981

LOCATION: Norfolk, Virginia

SOURCE OF INFORMATION: Watts Regulator Company "Stop Backflow"

SUMMARY: The removal of a damaged backflow preventer lead to salt water being pumped from a shipyard's saltwater fire protection system into the public water system.

DETAILS:

On January 29, 1981, a fast food restaurant complained to the water department that all their drinks were being rejected by customers as tasting "salty". The inspection by the water department found that the cold water used in making the drinks was chilled by passing through refrigeration coils and was automatically blended with other ingredients to make the drinks. The chilled water system as well as all potable water supply lines on the premises were inspected for cross connection, however, none were found.

A check was then made with adjacent water customers which revealed that an additional salty water complaint had occurred simultaneously at a waterfront ship repair facility. Both the restaurant and the shipyard were being served by the same water main lateral which, in turn, came off the main distribution line. A cross connection inspection of the shipyard revealed the following:

* The backflow preventer that had been installed on the service line to the shipyard had frozen and burst earlier in the winter. It had been removed and was replaced by a sleeve in order to maintain the water supply to the shipyard.

* The shipyard fire protection system consisted of high pressure sea water mains maintained by both electric and diesel driven pumps.

* The pumps were primed through the use of a city water line which was directly connected to the high pressure fire pump.

With the priming line left open and the first service pumps maintaining high pressure in the fire main, raw salt water was being pumped under positive backpressure through the sleeve into the public water distribution system.

To correct the problem, the city water primer line to the pumps was removed and a new backflow preventer promptly installed at the service line in place of the sleeve. Heat tape was wrapped around the backflow preventer to prevent future freezing.


1981-003

DATE OF OCCURRENCE: July, 1981

LOCATION: Robinson Township, Pennsylvania

SOURCE OF INFORMATION: Watts Regulator Company "Stop Backflow"

SUMMARY: Approximately three hundred residents of a housing development were without water for twenty-seven days following the backsiphonage of the insecticides Chlordane and Heptachlor into their water supply.

DETAILS:

The Allegheny County Housing Authority spent approximately $300,000 to replace the water piping, both inside and outside, in the Groveton Village housing development in Robinson Township, Pennsylvania. The housing development has twenty-three buildings, each consisting of four apartments. The water in the housing development was contaminated by the insecticides Chlordane and Heptachlor.

The insecticides entered the water system while an exterminator was applying it as a preventative measure against termites. The exterminator was mixing the chemicals in a tank truck with water supplied from a garden hose from one of the apartments. The end of the hose was submerged in the chemical solution at the time the water was shut-off. A plumber shut-off, then drained the water system to cut the 6-inch supply pipe to install a gate valve. The drainage point was downstream of the tank truck. Consequently, the chemicals were siphoned out of the trunk and fed into the water system.

The water supply to seventy-five apartments, housing approximately three hundred people, was contaminated. Repeated efforts to clean and flush the water piping were not satisfactory in removing the chemicals. It was finally decided to replace the water mains and all the potable plumbing in the apartments.

There no reports of illness. Residents of the housing development were told not to use any tap water for any purpose until the piping was replaced. The volunteer fire department provided drinking water supplied by tank truck. The residents were without water for twenty-seven days.


1981-004

DATE OF OCCURRENCE: August 24, 1981

LOCATION: Santa Ana, California

SOURCE OF INFORMATION: Orange County, California

SUMMARY: An incorrectly plumbed hydraulic press resulted in the backflow of oil into the city's water main.

DETAILS:

The following backflow incident occurred in Santa Ana, California on August 24, 1981. The incident was a result of an unprotected cross connection at a water cooled hydraulic press. This incident resulted in the backflow of an undetermined amount of oil based product into the city's water main. The sequence of events are as follows.

On the morning of August 24, a complaint was received by the Santa Ana Water Department. The customer, a sporting goods wholesaler, stated that the water in the employee restroom contained a high amount of what appeared to be oil. A visual examination of the water coming from the tap by inspectors from the water and health departments verified that a considerable amount of oil was present in the water.

After a thorough inspection of the commercial facilities adjacent to the warehouse, it was determined that the oil had entered the city's water main via an incorrectly plumbed hydraulic press. Apparently, during the replacement of one of the water cooled heat exchangers on the hydraulic press, the domestic water was inadvertently connected to the cooled oil return line which circulates the oil at 110 psi. Because the oil pressure was higher than the domestic water pressure, the oil was pumped into the domestic water line and subsequently into the city's distribution system.

After the cross connection was discovered the necessary corrections were made to the plumbing on the heat exchanger. The city's main line was then flushed to remove the remaining oil, and an approved backflow device was installed on the domestic water line to the heat exchangers.


1981-005

DATE OF OCCURRENCE: September, 1981

LOCATION: San Antonio, Texas

SOURCE OF INFORMATION: City of San Antonio, Texas

SUMMARY: An interconnection between the potable water system and a cooling system resulted in the contamination of the water to a pharmacy.

DETAILS:

On September 16, 1981 the Water Quality Division received a call from a pharmacy at a hospital complaining about a bitter taste in the water. An investigation revealed no chlorine residual and a slight bitter taste in the water. After running the water for approximately 30 minutes still unable to pick up chlorine residual.

The rest of the hospital and the fire hydrant out front had a 0.5 mg/L residual. The chief of maintenance was notified of the problem. There was only a single tap between the meter and the pharmacy. This tap served as a looped system used as cooling water. A single gate valve, in closed position, separated the potable water from the non-potable cooling water.

It was determined that the gate valve was not closing tight. The gate valve was removed and the line plugged. This solved that problem and a chlorine residual of 0.5 was established after flushing the water line.


1982-001

DATE OF OCCURRENCE: 1982

LOCATION: Shiawassee County, Michigan

SOURCE OF INFORMATION: Michigan Section - AWWA Newsletter

SUMMARY: Malathion contaminated a water distribution system due to backsiphonage through an aspirator type lawn sprayer.

DETAILS:

The Village of Bancroft in Shiawassee County faced a potentially hazardous situation in 1982, which demonstrates the importance of keeping distribution system valves in good working condition. The incident began with an old leaking fire hydrant that needed to be replaced. The hydrant could not be isolated for repair as the hydrant lead was not equipped with an isolating valve. The distribution system valves did not function after years without use. To repair the hydrant, the Village prepared for a shutdown of the entire distribution system. Customers were notified of the planned shutdown, but not everyone could be reached.

When the water system was shut down, one customer was beginning to use an aspirator type sprayer to apply Malathion insecticide to his lawn. The customer immediately noticed a drop in pressure while he was spraying. Seeking to find a kink in the garden hose that may have caused the pressure loss, the customer returned to the sprayer only to find the Malathion solution was gone.

Backsiphonage had drawn the Malathion into the hose, through the house plumbing and into the Village system. The customer recognized the hazard involved and immediately notified the Village superintendent.

The plan developed to correct the problem included public notification not to consume the water until further notice, a tank truck was provided as an alternate water source, and the system flushed and chlorinated.

This backsiphonage problem could have occurred regardless of the condition of the distribution system valves, but the possibility would have been greatly reduced if a small section of the system had been shut down or if a fire hydrant isolating valve had been provided. This problem also shows the need for public education about home cross connections. The aspirator type sprayer, although very popular, represents a hazardous cross connection. The aspirator should never be left unattended and should be disconnected if any drop in system pressure is noted. The installation of an atmospheric vacuum breaker on the outside hose bib may have prevented backsiphonage.


1982-002

DATE OF OCCURRENCE: 1982

LOCATION: Illinois

SOURCE OF INFORMATION: Watts Regulator Company "Stop Backflow"

SUMMARY: Ethylene Glycol backsiphoned from an air conditioning system's water holding tank into a group of Dialysis machines contributing to the death of several patients.

DETAILS:

A coroner's jury recently ruled in a large midwest city that renal dialysis machines that were accidently contaminated by anti-freeze solution in a large medical center were found to be a "significant condition" in the deaths of two patients. The deceased were two of six patients that underwent dialysis at the medical center in the Fall of 1982. One died the following day and the other died 16 days later.

Ethylene glycol entered the dialysis equipment through a series of events triggered when a manually operated valve was left open. The open valve permitted water to flow into a holding tank that was used to replenish a mix of glycol and water to the air conditioning system. With the valve partially open, water continually flowed slowly into the glycol/water mixture holding tank until it filled to a point where the pressure in the closed tank equaled the pressure in the water supply system. It is theorized that the pressure in the medical center's water system dropped allowing the glycol/water mixture to enter the system.

The filtration system on the dialysis machines are designed to remove trace chemicals such as those found in city water, however, the filtration systems could not filter the heavy load of chemical that it was suddenly subjected. The effect on the dialysis patients was dramatic; patients became drowsy, confused, and unconscious. They were promptly removed to intensive care where blood samples revealed a buildup of acid.

A test of the water supply to the filtration system quickly determined the presence of an "undesirable chemical". The defective (open) valve was then found that had permitted water containing glycol to drain from the air conditioning holding tank into the dialysis filtration system and from there into the dialysis machines.


1982-003

DATE OF OCCURRENCE: June, 1982

LOCATION: Springfield, Oregon

SOURCE OF INFORMATION: Springfield Utility Board

SUMMARY: Backflow through an irrigation hose resulted in insect larvae entering a food processing vat.

DETAILS:

A food processing plant employee came into the Water Department with an insect larvae that came out of the water hose used to wash down a processing vat. He said the larvae was alive and swimming when it entered the vat and lived for about 20 minutes in water chlorinated to 100 ppm. The vat was being sanitized prior to being used for another process.

The Water Department went to the processing plant and inspected all visible plumbing connections for cross connections that would allow access of larvae. Numerous cross connections were found. It was determined that the cause of backflow was a cross connection between the cold water feed line, a steam line and the irrigation system used to water outdoor planters in front of the buildings. All other identified cross connections would have allowed chemicals or food process fluids back into the system. The insect larvae (Primitive Crane Fly) entered the system through the irrigation piping.

A reduced pressure principle backflow prevention device was required on the main line to the plant. It was recommended that the irrigation service be re-plumbed, a vacuum breaker be installed downstream of the shutoff valve, and all other identified cross connections be eliminated or equipped with backflow prevention devices.


1982-004

DATE OF OCCURRENCE: October, 1982

LOCATION: Springfield, Oregon

SOURCE OF INFORMATION: Lane County Health Division

SUMMARY: A cross connection between the potable water system and a non-potable process water and fire system in a lumber mill was the probable cause of seven confirmed cases of Giardiasis.

DETAILS:

Information from the Lane County Health Division indicates that seven confirmed cases of Giardiasis have been documented among employees of a lumber company in Springfield, Oregon. The probable cause for this problem was a cross connection between the potable water system and a non-potable process water and fire system in the lumber mill.

An unauthorized connection was made at an edger which resulted in process water from a surface source contaminating the potable water at the lunchroom drinking fountain. Water samples collected at the mill's lunchroom showing an absence of coliform bacteria indicated that the cross connection had been eliminated.


1982-005

DATE OF OCCURRENCE: 1982

LOCATION: North Andover, Massachusetts

SOURCE OF INFORMATION: Watts Regulator Company, "Stop Backflow"

SUMMARY: The backflow of water containing hexavalent chromium occurred from a chiller in a large manufacturing plant.

DETAILS:

A well meaning maintenance mechanic, in attempting to correct a fogging lens in an overcooled laser machine installed a tempering valve and inadvertently caused the contamination of the water system in an electrical manufacturing plant in North Andover, Massachusetts. Hexavalent chromium was found at levels of 50 ppm. in the drinking water. This level is sufficient to cause severe vomiting, diarrhea, and intestinal sickness. Maintenance crews working during the plant shutdown were able to eliminate the cross connection and thoroughly flush the potable water system thereby preventing a serious health hazard from occurring.

A large refrigeration chiller that is used within the plant to primarily circulate chilled water for air conditioning purposes, supplied a portion of the water to a laser machine in order to keep its lenses cooled during the operation. The water used in the chiller system was treated with hexavalent chromium, a chemical additive used as an anti-corrosive agent and as an algicide to combat the buildup of bacteria in the closed loop, recirculated water system.

A maintenance mechanic, seeing that the lenses of the laser machine were becoming fogged as a result of being excessively cooled by the chilled water supply, installed a tempering valve in the chilled water piping leading to the laser machine. The tempering valve mixed the chiller water with hot water from the plants domestic hot water heater. During normal plant operation, the pressure balance at the tempering valve was such that the pressure from the chiller circulating pump was approximately equal to the pressure in the water line from the hot water tank. However, when the chiller pump required repairs, a temporary pump was installed. The temporary pump produced 150 psi pressure compared to the 60 psi potable water system pressure. The back pressure condition resulted in the backflow of the toxic chiller water into the water heater then into the plant's potable water system. Yellowish-green water started pouring out of the drinking fountains and into the washroom outlets


1982-006

DATE OF OCCURRENCE: August, 1982

LOCATION: Eastern U.S.

SOURCE OF INFORMATION: Watts Regulator Company "Stop Backflow"

SUMMARY: The backflow of propane gas into the city water system occurred when a water connection was left in place following the purging or a propane tank.

DETAILS:

Hundreds of people were evacuated from their homes and businesses on an August afternoon in a New England town. Fires were reported in two homes as a result of propane entering the city water system. One five room residence was gutted by a blaze resulting from propane gas "bubbling and hissing" from a bathroom toilet. In another home a washing machine explosion blew a woman against a wall. Residents throughout the area reported hissing, bubbling noises coming from washing machines, sinks and toilets. Faucets sputtered out small streams of water mixed with gas.

Located in the area is a propane plant consisting of 26 sub-surface 30,000 gallon capacity liquid propane storage tanks. City water provides both fire and domestic water service to the propane plant through an 8-inch combination service. It supplies two private fire hydrants.

The procedure that day was a "purging" of one of the propane tanks using water from one of the private hydrants located on the propane plant's property. There are two common methods for purging liquid propane tanks; using an inert gas such as carbon dioxide or using water. The use of water is preferred since it is more positive and will float out any sludge as well as gas vapors. In this case water was used from one of the private fire hydrants. The tank pressure was 85 to 90 psi and the city water pressure was 65 to 70 psi. The result was the backflow of the propane gas into the water main. It was estimated that the gas flowed into the water mains for about 20 minutes and that about 2,000 cubic feet of gas was involved. This was approximately enough gas to fill one mile of an 8-inch water main.


1982-007

DATE OF OCCURRENCE: March 1982

LOCATION: Tacoma, Washington

SOURCE OF INFORMATION: Tacoma Water Department

SUMMARY: A leaking single check valve permitted soapy water from a car wash to be pumped into the city water system.

DETAILS:

On March 17, 1982 the Tacoma Water Department received a call from a customer stating that his water was foamy and had a motor oil smell and little white bubbles. The customer had a combination service station, two-bay self-service car wash, office and residence.

During the inspection of the car wash the customer mentioned that the foamy water problem cleared up when the car wash was shut down. There was no backflow prevention device on the water line to the car wash.

On March 22, the customer advised that his maintenance man had found a (single) check valve leaking, allowing soapy water to be pumped into the rest of his domestic water system.

The customer was advised that a reduced pressure principle backflow prevention device must be installed on the water line to the car wash.


1982-008

DATE OF OCCURRENCE: November, 1982

LOCATION: Bangor, Maine

SOURCE OF INFORMATION: Watts Regulator Company "Stop Backflow"

"Bangor Daily News", Vol 93-No. 142

SUMMARY: The backflow of antifreeze from a hot water heating system occurred during the repair of a water main.

DETAILS:

A Bangor homeowner placed automobile antifreeze (e.g. ethylene glycol) in his hot water space heating (hydronic) system. He was heating his home with wood and feared that freezing would occur in sections of the unused hot water heating system.

Water district workers discovered the antifreeze when they shut off the water to the house to make repairs to the water main in the street. With the flow of water cut off, pressure in the lines in the house dropped and the antifreeze drained out of the heating system, into the water lines in the house, then into the water main in the street. Green water appeared at the point where the water main was being repaired. No one ingested the antifreeze.

The water connection to the hot water heating boiler was not equipped with a backflow prevention device.


1982-009

DATE OF OCCURRENCE: October, 1982

LOCATION: Monterey Park, California

SOURCE OF INFORMATION: Watts Regulator Company "Stop Backflow"

"Detroit Free Press", October 24, 1982

SUMMARY: The backflow of carbon dioxide resulted in approximately 200 people at a football game becoming ill.

DETAILS:

On October 22, 1982 approximately 200 people were diagnosed as suffering from copper sulfate poisoning after drinking soft drinks at a high school football game in Monterey Park, California. About 60 of the most seriously ill were taken from the football stadium by ambulance. Eight hospitals treated the patients for vomiting, dizziness, numbness and chills. Three patients were hospitalized overnight.

Those affected apparently had soft drinks at half time. As the first victims became ill, the crowd was warned over the public address system not to drink cola sold at concession stands.

The copper contaminant was the result of carbon dioxide from pressurized containers backflowing into potable copper water tubing.


1982-010

DATE OF OCCURRENCE: January, 1982

LOCATION: Wrangell, Alaska

SOURCE OF INFORMATION: Alaska Environmental Health Newsletter

SUMMARY: Copper laden water enters a carbonated beverage machine. possibly a result of drop in line pressure and backsiphonage of carbonated water into copper pipes.

DETAILS:

Two employees of a Wrangell restaurant became ill with nausea and vomiting on January 20, 1982, after consuming carbonated beverages from the food service beverage dispensing machine. Both reported an unusual taste to the beverages. The restaurant owner contacted the Ketchikan District Sanitarian for assistance in identifying the source of illness. Use of the machine was discontinued immediately.

Chemical analysis of tap water revealed pH of 6.6, total hardness of 60 and Ca hardness of 30. City records failed to identify any sudden fluctuation in chlorine residual concentrations or water pressure. Carbonated beverages were dispensed from a machine supplied by carbonated water produced in a system adjacent to the machine. Carbon dioxide gas from a pressurized tank was mixed with water to form carbonated water used in the soft drink dispenser. No check valve was installed on the copper line installed five or six years before to replace a leaking plastic line. Syrups, mixes and city water were sampled for copper levels on January 21. Significantly high levels were detected in all mixes with values ranging from 16-63 ppm. Syrup and tap water levels were less than 0.1 ppm.

Prior to this incident there was no significant decrease in water pressure in the City of Wrangell, although there were some breaks in water lines at individual residences due to unusual cold. Reservoir levels also fluctuated with a drop in line pressure and backsiphonage of carbon dioxide and carbonated water into the copper water line supplying the building. As a result, copper could have leached from the potable water line. When normal pressure was restored, copper laden water could then have entered the carbonated beverage machine. Copper lines in the machine could have contributed additional copper to mixes.

A check valve was installed on the water supply line, the drink machine was cleaned and the operator was advised and instructed to replace the copper line with plastic line immediately. Mixes continued to be sampled until levels were less than 1.0 ppm.


1983-001

DATE OF OCCURRENCE: 1983

LOCATION: Eastern U.S.

SOURCE OF INFORMATION: Watts Regulator Company "Stop Backflow"

SUMMARY: A ship's salt water fire system Pumped river water Into a shipyard's water supply system.

DETAILS:

Water fountains at an east coast shipyard were posted "No Drinking" as workers flushed the water mains to eliminate raw river water that had entered the shipyard following contamination from an incorrectly connected water line between a ship and the shipyard's fire hydrant. The shipyard trucked in potable water so the employees could obtain drinking water. However, some third shift employees drank the river water before the pollution was discovered and later complained of stomach cramps and diarrhea. Fortunately the contamination was confined to the area of the shipyard complex and did not enter the adjacent city water system.

The cause of the problem was a direct cross connection between the on board salt water fire protection system on the ship and the domestic water system on the dock. While the shipyard had been aware of the need for backflow protection devices at the dockside area, the devices had not been delivered and installed prior to the time of the incident. As a result of ship's fire pump being operated at greater pressure than the potable shipyard system, river water backflowed into the shipyard's system.


1983-002

DATE OF OCCURRENCE: October,1983

LOCATION: Vancouver, Washington

SOURCE OF INFORMATION: Vancouver Water Department

SUMMARY: A cross connection in a dental office resulted in air being pumped through a hand held aspirator into the building's domestic water system then into the surrounding neighborhood.

DETAILS:

On October 26, 1983 numerous complaints were received at the Water Dispatch Center in Vancouver, Washington about air in the water. One lady had asked if her water had been shut off, all she was getting through the faucet was mostly air. A water employee was dispatched to the address. After talking to other surrounding neighbors, it was determined that the same problem existed for other homes.

After reviewing the area, no physical outside work by any contractor was going on. On that same two block area was a church and a dentist office. The cross connection was determined to have come from the dentist office. Earlier that morning, the owner had installed a new air compressor. The water pressure was 60 psi, and their old compressor would shut off at 60 psi. The new air compressor was set to shut off at 90 psi. The leak was in the line that fed the hand-held aspirator which is used to rinse and blow out filings from drilled teeth. The hose consisted of a hose inside a hose designed similar to a single wall heat exchanger.

After the owner was notified of the problem his only remark was "no wonder the air compressor would shut off for short periods".

The owner was requested to install an R.P.B.D. to separate and protect the water system, the building and his patients from the dental office equipment.


1983-003

DATE OF OCCURRENCE: June, 1983

LOCATION: Woodsboro, Maryland

SOURCE OF INFORMATION: Watts Regulator Company "Stop Backflow"

SUMMARY: The herbicide Paraquat was siphoned into the town's water distribution system.

DETAILS:

In June 1983, the water pressure in the Town of Woodsboro was temporarily reduced due to the failure of a pump in the water system. Coincidentally, a gate valve between a herbicide holding tank and the town's water system had been left open. The cross connection permitted the powerful agricultural herbicide Paraquat to be siphoned into the water distribution system. Upon restoration of the water pressure, the herbicide flowed throughout much of the town's water system.

Residents were warned by the fire department not to use water for cooking, bathing, drinking or any other purpose except for flushing toilets. The town undertook an extensive program of flushing the water system, water sampling, and emergency supply of drinking water from tank trucks.

No serious illness or loss of life was reported.


1983-004

DATE OF OCCURRENCE: 1983

LOCATION: Brandon, Manitoba

SOURCE OF INFORMATION: Western Canada Water & Waste Association

SUMMARY: Following a reduction in water system pressure, a faulty valve permitted the backflow of a caustic chemical solution from a boiler.

DETAILS:

In 1983, a college in Brandon, Manitoba had its water contaminated due to a faulty valve. Maintenance personnel were flushing the school's boiler system with a caustic chemical when pressure suddenly reduced in the city's water main, resulting in yellowish water at the spout.


1983-005

DATE OF OCCURRENCE: 1983

LOCATION: San Antonio, Texas

SOURCE ON INFORMATION: City of San Antonio, Texas

SUMMARY: The back-siphonage of a chemical in a manufacturing plant resulted in damage to plastic water piping in the plant and to RPBA isolating the plant.

DETAILS:

On January 27, 1983 a call was received by the Water Quality Division from a plumber regarding a chemical back-siphonage at a manufacturing plant in New Braunfels, Texas. He said they had been contacted to replace the water softener and plastic water lines because the chemical which was back-siphoned had dissolved all the plastic with which it came in contact.

The plant had a reduced pressure principle backflow preventer installed on the service. From the description by the plumber, evidently when the water department lost their water pressure, the #2 check valve failed on the backflow preventer. This is surmised because the plumber said the water from inside the building drained out through the relief valve on the RPBA assembly.

The plumber was concerned that the chemical had also dissolved part of the backflow preventer. The plumber was advised to also replace the plastic and rubber parts within the backflow preventer.


1984-001

DATE OF OCCURRENCE: 1984

LOCATION: Oregon

SOURCE OF INFORMATION: Oregon Health Div. "Pipeline" Vol 1, No 3

SUMMARY: An interconnection between the potable water lines and the fire supply lines in an Oregon plywood mill lead to several cases of gastrointestinal illness among the mill workers.

DETAILS:

The manager of a plywood mill requested the county health department to sample the drinking water of the mill after receiving complaints from employees about its "milky white" appearance. Working with the city water department, the county sanitarian collected samples from the mill and another location in the city. Though the mill receives city water, samples showed a zero chlorine residual. In contrast, a nearby location in town had clear water with a free chlorine residual of 0.3 mg/L.

The following day, an unusually large number of employees stayed home from work, with a majority reporting similar symptoms of nausea and severe diarrhea. Bacteriological sample results were reported the day after: five tubes positive and fecal coliform present in the mill's water sample, while the sample from the nearby location in town was negative.

In addition to the city water supply, the mill also draws water from an adjacent river to supply its fire system. Booster pumps maintain the fire system pressure at about 125 psi. The water from the city enters the mill at about 70 psi.

The mill's maintenance personnel examined the piping system for a cross connection. Their investigation was hampered by incomplete and inexact piping system drawings. They located three interconnections between the fire and potable water systems with the gate valves open. Further investigation found that the mill's recent water use had been exceptionally low; 10 cubic feet per month instead of the 7000-9000 used by comparable mills. The conclusion was reached that the mill employees had been drinking untreated river water via a cross connection.

A single check valve was located at the mill's connection to the city, it is assumed that this prevented contaminated river water from entering the city's mains. Because of the difficulty in locating all possible cross connections, the mill decided to install all new potable water lines. An approved RPBA was installed on the water connection to the city system.


1984-002

DATE OF OCCURRENCE: February, 1984

LOCATION: Riverbend, Oregon

SOURCE OF INFORMATION: Oregon Health Division

SUMMARY: A domestic hot water system was contaminated via a cross connection with a solar hot water heating system.

DETAILS:

On February 13, 1984 the Oregon Health Division received a call from a resident of a mobile home park. The resident described his water as having an oily substance mixed with it.

On February 15, the home was visited by a member of the Health Division. Water from the tap had substantially improved and had no visible impurities. A sample of tap water was saved by the home owner. The water was cloudy white, with a layer of yellow oil floating on the surface. Only the hot water tap had produced such oily water.

The operator of the Riverbend Water System reported a few shut downs of the entire system had occurred in the December to February period because of freezing weather.

The evidence pointed to a problem isolated to the individual home, not the water system. The hot water tank was drained to observe its contents. A very slight amount of oily film was present on the surface of the water from the tank.

The home had a solar hot water heater. It was concluded that this was the probable source of the contaminant. Support for this conclusion was added when the home owner stated that their solar hot water system had not been operating properly.

On February 17, an employee of a local heating company inspected the solar hot water system. It had less than 10 percent of its freon charge. The tank was found to be cracked and the gas line was filled with water.

The heat exchanger was of the single wall construction type. It was a gas system which uses dichloroflouromethane. Mineral oils are used in the system. Dichloroflouromethane is not considered toxic; however, any chlorinated compound is suspect from a health standpoint.


1984-003

DATE OF OCCURRENCE: February, 1984

LOCATION: Seattle, Washington

SOURCE OF INFORMATION: Seattle Water Department

SUMMARY: Air conditioning make up water containing the corrosion inhibitor Nitrate-Borate was pumped into a high rise office building's water system then into the city's distribution system.

DETAILS:

On February 10, 1984 the recirculating pump failed on an air conditioning unit in a high rise office building in downtown Seattle, Washington. The building contained a major computer facility.

To save valuable computer files, the buildings's maintenance staff improvised a water-to-waste air conditioning loop. A 3/8-inch garden hose was run 50 feet from a hose bib in an adjoining parking area to a drain on the air conditioning piping. A second hose was run from another drain connection to a convenient sump, thereby establishing a once-through air conditioning system using Seattle's cold domestic water. This improvised system by-passed the reduced pressure principle backflow prevention device installed on the water supply line to the air conditioning system.

While the air conditioning unit's pump was removed for repairs, a temporary replacement pump of higher horsepower was installed. The drain hose was removed, but the maintenance staff forgot to remove the 3/8-inch supply hose. The temporary pump provided a much higher pressure that the Seattle water system, resulting in the backflow of air conditioning water into the water main in the street.

The air conditioning water contained the corrosion inhibitor Nitrate-Borate. The corrosion inhibitor was detected in the bank building across the street from the high rise office building. The Seattle Water Department initiated a water main flushing program and isolated the high rise office building. The water system contamination was limited to a very small area, but rumors grew and the mayor's office was flooded with calls from restaurants, hotels, etc.


1984-004

DATE OF OCCURRENCE: August, 1984

LOCATION: Bellevue, Washington

SOURCE OF INFORMATION: Bellevue Public Works/Utilities Dept.

SUMMARY: The temporary shut down of a water service to a nursing home resulted in the back siphonage of sodium silicate into the building's potable water system.

DETAILS:

On August 4, 1984 the City of Bellevue had to shut down the water supply to a nursing home as a result of a valve repair. The water main was shut down about an hour. When water service was resumed, the residents of the nursing home notified Bellevue Water of burning sensations in their mouths.

The temporary pressure loss caused an injector to introduce a large amount of sodium silicate into the water supply lines, and when pressure was restored, the high concentration of anti-corrosive in the water was carried throughout the plumbing system. There was no backflow prevention device on the injection system to the boiler.

The nursing home ceased use of the city water for 3 days, until after the main and their service were flushed thoroughly, and subsequent samples proved the water safe to drink. Other than a few temporary upset stomachs and a burning sensation in their mouths, no one was seriously ill or injured from the experience. Shortly after a R.P.B.D. was installed upstream of the injection feed system to the boiler.


1984-005

DATE OF OCCURRENCE: March, 1984

LOCATION: Vancouver, Washington

SOURCE OF INFORMATION: Vancouver Water Department

SUMMARY: During the shut down of a water main to repair a valve, the backflow of water from a nursing home's boiler caused burns to a Water Department employee's hands.

DETAILS:

On March 1, 1984 a 4-inch valve was reported to have developed a leak. The valve is tapped into a 6-inch main line. It became necessary to isolate the 4-inch valve in order to replace it. The only means of isolating the valve was to shut down the 6-inch main at the nearest intersection and go up hill approximately three blocks to shut off the other end of the 6-inch main. After notifying customers, an employee working on removing the valve got his hands burnt from hot water running from the open 4-inch main.

After a short length of time, the source of the backflow had been determined to be a nursing home located approximately 50 feet higher in elevation than the damaged 4-inch valve. The nursing home had three 250 gallon domestic hot water boilers. All three of the boilers were used for hot water in the kitchen, showers, etc.

After establishing personal contact, the Water Department sent a letter notifying the owners that the three domestic hot water boilers needed to be isolated with State approved double check valve assemblies along with new temperature/pressure relief valves.


1984-006

DATE OF OCCURRENCE: January, 1984

LOCATION: City of Manhattan, Kansas

SOURCE OF INFORMATION: AWWA "Backflow Prevention", July 1989

SUMMARY: The backflow of boiler water containing a chromate anti-corrosive chemical occurred at an elementary school during the repair of a main break.

DETAILS:

On January 18, 1989, the Riley County Health Department was contacted by a school district and requested to sample drinking water at one of their elementary schools. Reportedly, a backflow of boiler water containing an anti-corrosive chemical had occurred during the repair of a water main break the previous night.

Because of the very cold temperatures, a 4-inch cast iron water main froze and broke outside the school building. The maintenance crew isolated and repaired the break. After the water pressure was restored, one of the workmen took a drink of the water from a drinking fountain and noticed a foul taste. The maintenance crew realized that contamination of some type had occurred.

The maintenance crew determined that boiler water (maintained at about 12 psi) had backflowed past the pressure regulator into the potable water system when the water main was shut off to repair the break. At that time, flushing was begun and continued for several hours until the school opened the next day. Water was turned off at drinking fountains and students were warned not to drink from sinks.

The Kansas Department of Health and Environment determined that the anti-corrosive chemical was a chromate compound. No one was injured in the incident.

Subsequently, the County Health Officer issued and order to provide backflow protection at each school in the County. Although all other schools in the County began corrective action, the school district where the incident occurred issued a statement that the installation of backflow preventers were an unnecessary requirement and refused to comply with the order. The local newspaper obtained a copy of this statement and reported the circumstances. From that point on, compliance was obtained.


1984-007

DATE OF OCCURRENCE: February, 1984

LOCATION: Salem, Oregon

SOURCE OF INFORMATION: Utility Assistance Co.

SUMMARY: The backflow of hot water from a boiler in a building operated by a diaper service resulted in the melting of the building's 2-inch polyethylene service line.

DETAILS:

On August 15, 1983 during the changing of the water service pipe at a diaper service company, a backflow of hot water occurred while the service pipe was disconnected. During the course of the investigation, the City of Salem was informed that the business was in the process of relocating in about 3 or 4 months. With this condition in mind, the city did not feel it feasible to immediately require the installation of a backflow prevention device. A device was ordered and installed when the relocation occurred on or by July, 1984, whichever happened first.

On February 15, 1984 the boiler within the facility overheated, resulting in the backflow of water from the boiler. The control box seal had leaked, shorting out the controls for the burner element of the boiler. The pressure relief valve had also failed, allowing the pressure in the boiler to increase to a level higher than the city's supply pressure. The high pressure forced hot water backwards into the water service, causing the polyethylene line to melt and discharging water from both the city's main and the boiler.

Following the incident, the 2-inch water meter to the facility was removed and water service was temporarily provided with a hose and a city supplied 3/4-inch reduced pressure principle assembly. The owners were notified to install a reduced pressure principle assembly on the service line before the 2-inch service would be reconnected.


1984-008

DATE OF OCCURRENCE: June, 1984

LOCATION Farmington, New Mexico

SOURCE OF INFORMATION: Watts Regulator Company "Stop Backflow"

SUMMARY: A leaking single check valve on a boiler feed line resulted in a school's potable water system being contaminated with the toxic corrosion inhibitor sodium dichromate.

DETAILS:

The Farmington High School was closed for several days, when it was noticed by a home economics teacher, that the water in the school was a yellow color. The teacher covered the school's drinking fountain with towels before school started, and notified authorities.

The city chemist determined that the water samples taken in the school contained levels of chromium as high as 700 ppm; the maximum content contaminant level is 0.05 ppm. The chemical was identified as sodium dichromate, a toxic form of chromium.

No Students or faculty were known to have consumed any of the contaminated water.

Investigation disclosed that the sodium dichromate was used in the school's heating system boilers to inhibit corrosion. The superior pressure in the boiler, combined with a leaking single check valve on the boiler feed line, resulted in the backflow of the chromate solution into the school's potable water system.


1984-009

DATE OF OCCURRENCE: November, 1984

LOCATION: Macon, Georgia

SOURCE OF INFORMATION: Watts Regulator Company "Stop Backflow"

SUMMARY: Creosote, backsiphoned through a 3/4-inch hose used to prime a pump, contaminated a section of a municipal water system.

DETAILS:

On November 17, 1984 a wood preservative company in Macon, Georgia requested the water purveyor to turn off one of their two water service connections so that repairs could be made to one of their private fire hydrants. Later in the day, the company requested that the service be resumed. Within two hours, customer complaints were being received of bad tasting water.

The wood preservative company, as part of their operation, pumped creosote from a collection pit to other parts of their operation. The pump automatically shuts off when the creosote in the pit is lowered to a predetermined level. After the creosote returns to a higher level, the pump restarts. This pump, however, often would lose its prime prior to the pit refilling. To prevent the loss of suction pressure, the wood preservative company connected a hose from a 3/4-inch hose bib located on the fire service line to the suction side of the pump. The hose bib remained open continuously in an effort to keep the pump primed.

The request to turn off the water service was necessary to repair a fire hydrant. To remove the hydrant the fire line was drained. The creosote was backsiphoned through the 3/4-inch hose connection during the draining of the fire line. When the fire line was later filled with water, the creosote contaminated water flowed through the fire system into a section of the municipal water system.

The water purveyor flushed the municipal system until analysis indicated that the water was free of contamination. Residents were notified to flush their plumbing systems for thirty minutes and that their water bills would be adjusted accordingly.


1984-010

DATE OF OCCURRENCE: Summer, 1984

LOCATION: Edmonton, Alberta

SOURCE OF INFORMATION: Western Canada Water & Waste Association

SUMMARY: Three leaking check valves at a Light Rapid Transit station allowed polypropylene to enter the water system.

DETAILS:

During the summer of 1984, personnel at a LRT station in Edmonton, Alberta complained about smelly, grey and bad tasting water. Some people developed stomach problems. When the Edmonton Water and Sanitation Department was alerted about the situation, water samples were taken/ The lab results showed a presence of polypropylene glycol in the water.

The investigation of the system showed that the three check valves installed on the system were all leaking. The installation of the proper backflow prevention device (double check valve) cleared up the problem.


1985-001

DATE OF OCCURRENCE: June, 1985

LOCATION: Yakima, Washington

SOURCE OF INFORMATION: Department of Social and Health Services

State of Washington

SUMMARY: A cross connection with an irrigation system resulted in the pesticide contamination of a well supplying four residences.

DETAILS:

On June 5, 1985 a resident of Yakima, Washington notified the local Health District office that the water system to his house was contaminated with a pesticide and possibly a fertilizer. The pesticide was thought to be Guthion and the fertilizer was U.N.-32.

The source of water was a well that provides water to four residences and an orchard operation. Occasionally, the well is used as a back-up irrigation water source and for spring frost control.

A cross connection occurred as a result of chemical application through overhead sprinklers used to irrigate orchards. Irrigation water comes from a canal, and the chemicals are added as the water is pressurized. The orchard owner made an interconnection from the domestic water line from the well to the irrigation system. The higher pressure from the irrigation pump pushed water through this interconnection into the domestic water system and then into the well.

The orchard owner was ordered not to use water from the well until the well and domestic water system could be cleaned and retested for contamination. The interconnection was ordered disconnected.


1985-002

DATE OF OCCURRENCE: May, 1985

LOCATION: Olympia, Washington

SOURCE OF INFORMATION: Department of Social and Health Services

State of Washington

SUMMARY: The contamination of an office building water system with a cleaning compound was the result of a cross connection to an air conditioning system.

DETAILS:

On May 29, 1985 a complaint was received from the local Health District office that water in an office building's ice machine was "blue and foaming".

An inspection of the building found a cross connection between a "dry tank" make-up water tank to the air conditioning system and the building's domestic water system. Although the air conditioning system was new (replacement of an old system), the make-up water connection existed for some time. The pump on the new air conditioning system was of higher horsepower and provided a higher pressure than the city water system. The new air conditioning system was being tested with a cleaning solution containing sodium metasilicate and ethoxylated nonionic surfactant when the backflow incident occurred.

No reports of illness were made to local health officials.

The buildings water system was flushed and the cafeteria where the "blue water" was reported closed and all of its products made with water discarded.


1985-003

DATE OF OCCURRENCE: July, 1985

LOCATION: Arpelar, Oklahoma

SOURCE OF INFORMATION: "Rural Water Magazine", Vol 6, No 2

SUMMARY: A break in a water line caused the backsiphonage of a mixture of Chlordane, Malathion, Sevin and Diazanon into a portion of the water system service Arpelar, Oklahoma.

DETAILS:

On July 12, 1985 a portion of the water lines of Arpelar Rural Water District No. 7 of Pittsburg County, Oklahoma were contaminated when a water hose was left inside a 200 gallon tank containing Chlordane, Malathion, Sevin and Diazanon. While the tank was being filled, a drop in water pressure, due to break in the line, caused backsiphonage of the chemicals into the line.

When health officials were notified on July 13, of the problem in Arpelar their outlook was grim. Never before had health officials been able to completely remove Chlordane from a water line. This problem was compounded due to the requirement that no trace of Chlordane be left in the water because of possible health effects after prolonged exposure to the pesticide.

On July 13, the State Department of Health requested that the affected homes not use the water for any purpose other than flushing toilets. The water lines were flushed and samples taken for chemical analysis. The results showed that pesticides were still present.

Between July 17 and 20, Chlorine was injected in the lines and left for a day, then the water lines and house were flushed. Water samples showed no signs of any of the chemicals other than Chlordane, of which significant amount still remained.

Between July 25 and 27, a caustic soda treatment was used followed by flushing. Although each treatment reduced the amount of Chlordane in the system, traces were still present.

On August 3, a detergent used by the dairy industry to remove milk fat from milk line was added to the system, and the system flushed. The detergent treatment was repeated three times. On September 16, the water lines were declared clean.

This cross connection cost Arpelar, Oklahoma approximately $100,000.


1985-004

DATE OF OCCURRENCE: July, 1985

LOCATION: Fife, Washington

SOURCE OF INFORMATION: City of Fife

SUMMARY: A direct connection between a hose bib and a sewer resulted in the backsiphonage of sewer gases/sewage into a single family residence.

DETAILS:

Following a break in a water main in a residential neighborhood, the City of Fife's Department of Public Works received several complaints from one resident of bad tasting water. Only one resident in the neighborhood complained of bad tasting water.

The investigation of the complaint found that the owner of the home had a leaky faucet in the back yard. Instead of fixing the problem, the owner attached a garden hose to the faucet and drilled a hole in the sewer along the side of his house and stuffed the hose down the sewer. When the water main broke, backsiphonage occurred, causing the backflow of sewer gases or sewage through the hose bib and into the house.


1985-005

DATE OF OCCURRENCE: March, 1985

LOCATION: New York

SOURCE OF INFORMATION: "Morbidity and Mortality Weekly Report"

SUMMARY: The backflow of ethylene glycol from an air conditioning system into the potable water supply line to a dialysis machine resulted in the death of a patient.

DETAILS:

In March 1985, a 52 year old hospitalized woman died one day after being exposed to ethylene glycol during a session of hemodialysis for chronic renal failure. Review of the events preceding the accident revealed that the hospital's potable water system, which was the source of water used to prepare dialysis fluid, had been inadvertently contaminated when the air conditioning system was flushed with a commercial solution that is 95 percent ethylene glycol and contains a marker dye.

Contrary to the municipal building code, there was a direct line connection between the potable water system and the chilled water circuit of the air conditioning system. This cross connection was open for flushing of the chilled water circuit when the chilled water pump was activated. A check valve in the line failed to prevent backflow from the pressurized circuit into the potable water system. Despite its being detected elsewhere in the hospital, contamination of the potable water went unrecognized in the dialysis unit.

The patient was noted to be somnolent (sleepy) after her final dialysis session, but ethylene glycol intoxication was not suspected until coma, metabolic acidosis, and irreversible shock developed 12 hours later. One other patient had been dialyzed on the same day as the injured patient, but showed no evidence of ethylene glycol exposure. One hospital worker had taken a sip of contaminated water, but had not swallowed it because of its taste and obvious discoloration. No other exposures were reported.


1985-006

DATE OF OCCURRENCE: September, 1985

LOCATION: Sacramento, California

SOURCE OF INFORMATION: Daily Democrat, October 6, 1985

California Dept. of Health Services.

SUMMARY: The pesticide Malathion used by a grain elevator to spray grain as it is loaded into ships, was pumped into the public water system through a faulty check valve.

DETAILS:

On September 5, 1985 a grain elevator in the Port of Sacramento was spraying grain as it was being loaded onto a ship with the pesticide Malathion. The spray was turned off but not the chemical pump, forcing contaminated water back through the port's water system and into the East Yolo Community Service District distribution system. The service district supplies water to nearly 5000 customers in West Sacramento, Broderick and Bryte.

The grain elevator was following a common practice of obtaining the water for spray application of the pesticide from a fire hydrant. Two check valves installed to prevent backflow of the mixture apparently failed, allowing an estimated 2 gallons of the pesticide to enter the potable water system.

An inspector at a nearby beverage company noticed that something was wrong with the water and notified the State Health Department.

The Sacramento Port District notified all ships in the port or that had been in port of the problem and that if any ship took on water, that their water system could be contaminated.

The East Yolo C.S.D. isolated the mains in the area and began a flushing program to remove the contaminated water. The State Health Department contacted the local news media to issue a warning to the residents not to drink the water.

Samples collected from the distribution system near the port showed a maximum concentration of Malathion of 16 parts per billion (ppb), well below the State's "action level" of 160 ppb.


1985-007

DATE OF OCCURRENCE: November, 1985

LOCATION: Grand Prairie, Texas

SOURCE OF INFORMATION: Environmental Health Department,

City of Grand Prairie

SUMMARY: The backflow of xylene and ethylbenzene from an unknown source resulted in contamination of the water supplied to several customers of a municipal water system.

DETAILS:

On November 11, 1985 the Environmental Health Dept. received a telephone call from a propane gas distributor complaining of cloudy water in their office. Water division personnel collected a water sample and flushed a nearby fire hydrant for half an hour. The sample was milky white and had an odor similar to paint thinner. A door-to-door survey was conducted of over 20 businesses in the area. A total of 10 buildings were found to have contaminated water, including one apartment complex. During the inspection, notices of violation for direct cross connections were issued at two businesses.

The Public Works Dept. began flushing the water in the affected area. During this time, additional complaints were received from businesses, a fire station, and a residence in the same vicinity.

The Nov. 13, laboratory report identified xylene and ethylbenzene in the water sample. The lab. later reported the concentrations to be 118 ppm & 17 ppm, respectively. Both substances are petroleum derivatives used in paint, glue, adhesive, and cleaning compounds. Although little data was available on the possible toxic effects of ingesting either chemical in dilute concentrations, it was believed that the amount of substances in the water supply would present no danger. The 12 follow-up samples collected from representative points in the affected area were reported free of the two substances. The Food & Drug Administration took samples from five food processors in the area to check for possible contamination of their products. These companies had voluntarily withheld their products after learning of the problem. The laboratory tests revealed some contamination of the products sampled at all food processors. Although the contaminants were in the parts per billion range, all the products were destroyed.

In the following two week period, it became evident that the attempt to identify the source of contamination would be unsuccessful. Following this incident, it was recommended that the city pursue the initiation of a cross connection control program.


1985-008

DATE OF OCCURRENCE: January, 1985

LOCATION: Salem, Oregon

SOURCE OF INFORMATION: City of Salem and Utilities Assistance Co.

SUMMARY: Undersized piping appeared to be the cause of back-siphonage of anti-freeze from a fire suppression system.

DETAILS:

On January 8, 1985 the City of Salem inspected a warehouse because of the change in the business leasing the building. The unheated warehouse contained an anti-freeze filled fire suppression system supplied by the domestic water meter. As a result of the inspection, the owners were notified to install a reduced pressure principle assembly on the fire system.

On January 24, two days before the reduced pressure principle assembly was scheduled to be installed, the owner of the new business was washing down the parking lot with a garden hose attached to a hose bib located approximately four feet upstream of the fire system connection. The business owner noticed green anti-freeze coming out of the hose. He knew the anti-freeze came from the fire system, hence did not feel it necessary to call the city. On January 26, when the city inspected the new reduced pressure principle assembly, the business owner informed the inspector of the backflow incident.

The backsiphonage into the garden hose appeared to have been caused by undersized piping within the building.


1985-009

DATE OF OCCURRENCE: April, 1985

LOCATION: Melrose Park, Illinois

SOURCE OF INFORMATION: "FDA Consumer", February 1986

SUMMARY: Approximately 16,000 persons became ill and two deaths resulted from an "industrial" cross connection that contaminated milk produced from a dairy in Illinois.

DETAILS:

The following incident illustrates that cross connections also occur in industrial operations. Piping systems containing products assumed to pose no health hazard if found cross connected to the potable water system, may become a health risk.

At least 16,000 people in Illinois, Michigan, Minnesota and Wisconsin are known victims of an outbreak of Salmonella typhimurium spread through milk from a dairy in Melrose Park, Illinois. One of the microbiological characteristics of this organism was its resistance to certain antibiotics.

The Illinois Department of Health stated the contaminated milk was the direct cause of the deaths of two persons, and the indirect cause in the deaths of four, possibly five, people.

The source of the contamination was an "industrial" cross connection within the dairy, totally unassociated with the potable water supply.

A two foot section of pipe was found connected between the piping system carrying unpasteurized milk and the system carrying pasteurized skim milk. Closed valves at each end of the ten foot pipe section were supposed to prevent unpasteurized milk from mixing with pasteurized products. The two valves were believed to have been left open after a cleaning and sanitizing operation.


1985-010

DATE OF OCCURRENCE: July, 1985

LOCATION: Tampa, Florida

SOURCE OF INFORMATION: City of Tampa, Florida

SUMMARY: A direct connection between a water softener drain line and the sewer may have resulted in the contamination of a home's drinking water.

DETAILS:

In April, 1985 a water softener was installed on the water service to a residence for pre-treatment for water supplied to a kidney dialysis machine. On July 6, the home experienced a sewer blockage and called a plumber to clean the 4-inch sewer line.

On July 7, after another blockage, the plumber was called back to clean the line again. The plumber discovered that a hole was drilled in the top of the sewer line, and the drain line from the softener was inserted through the hole.

The homeowner became suspicious that the unusual virus both he and his son had recently acquired may have been the result of the cross connection. Both were being treated for a viral infection at the local hospital.


1985-011

DATE OF OCCURRENCE: 1985

LOCATION: Chelmsford, Massachusetts

SOURCE OF INFORMATION: Howard D. Hendrickson

SUMMARY: Car wash water backflows into city water mains.

DETAILS:

Car wash process water backflowed into the city water distribution mains. A recirculating water system was used at the car wash and when a city water make-up valve was left open, the wash water entered the potable water supply through an unprotected cross connection.


1985-012

DATE OF OCCURRENCE: 1985

LOCATION: Boston, Massachusetts

SOURCE OF INFORMATION: Howard D. Hendrickson

SUMMARY: Chemically treated water from a cooling tower backflowed into potable water supply of a condominium complex.

DETAILS:

Chemically treated water from a cooling tower backflowed into the potable water system of a condominium complex through an unprotected city water make-up line. Initial samples indicated 125 PPM hexavalent chromium in the potable water system. Over 600 residents consumed bottled water for three days until appropriate devices were installed and further sampling indicated water was safe for domestic use.


1985-013

DATE OF OCCURRENCE: 1985

LOCATION: Boston, Massachusetts

SOURCE OF INFORMATION: Howard D. Hendrickson

SUMMARY: 500-1000 gallons of ethylene glycol and hydrazine treated water backflowed into a hospital domestic water system and city mains.

DETAILS:

An estimated 500-1000 gallons of water treated with ethylene glycol and hydrazine backflowed into the domestic water system of a regional hospital and the water mains in the street. The treated water backflowed through a temporary hose connection after repairs were made to the chilled water system. Hydrants on the system and taps in the building were flushed until lab tests confirmed contamination was eliminated.


1986-001

DATE OF OCCURRENCE: January, 1986

LOCATION: Bonner Springs, Kansas

SOURCE OF INFORMATION: American Backflow Prevention Association

"Backflow Prevention"

Vol. 3, No. 4. April, 1986

SUMMARY: Two employees of a grain mill became ill after drinking water contaminated with the pesticide Malathion.

DETAILS:

Two employees of a grain mill in Bonner Springs, Kansas were taken to a hospital on January 10, 1986 after they became ill from drinking water contaminated with the pesticide Malathion. The plant mills various cereal products. The grain arrives in railroad hopper cars and shipped from the plant in bags and packages. It is normal procedure to treat all raw grain with a pesticide before other processing is started.

An aspirator device is used to feed a pesticide, such as Malathion, and dilute it with water to the proper application strength. The aspirator uses city water pressure. During spraying, the Malathion was drawn into the plant's plumbing. The city official that arrived shortly after the backflow incident reported that the basement floor contained standing water, which suggested a plumbing leak may have caused "irregular" water pressures within the plant's water piping. City officials maintained that there was never a drop in pressure within the city's distribution system. The city assisted plant personnel in flushing the plumbing system and directed the company to discontinue use of the aspirator device until protection could be provided to prevent backflow.


1986-002

DATE OF OCCURRENCE: March, 1986

LOCATION: Victoria, British Columbia

SOURCE OF INFORMATION: Victoria Water Department

SUMMARY: The domestic water system in the Provincial Museum was contaminated by the backflow of water from an air conditioning/humidifier unit that contained a corrosion inhibitor.

DETAILS:

In March, 1986 the City of Victoria Water Department received a complaint from the Provincial Museum that their water "Smelled of ether". The odor was a reoccurring problem, with its strongest level being noticed in the early morning.

The inspection of the museum confirmed the odor. By following the water system to the area of the strongest odor, it was concluded that the source was the museum's air conditioning/humidifier unit installed in the basement. The make-up water tank for this unit contained a corrosion inhibitor that smelled like ether. The unit's pump operated at a higher pressure than the city water pressure.

A reduced pressure principle backflow prevention device was ordered installed on the water connection to the air conditioner/humidifier unit and the water system ordered flushed.


1986-003

DATE OF OCCURRENCE: April, 1986

LOCATION: Withrow, Washington

SOURCE OF INFORMATION: "Wenatchee World" newspaper

SUMMARY: The residents of Withrow, Washington were without water for four days after herbicide 2,4-D was siphoned into the community's water system.

DETAILS:

On April 28, 1986 the Withrow water system was contaminated by a farmer that tried to fill his spray tank with water to dilute the herbicide 2,4-D. The pressure in the water system at the time was below atmospheric, hence the contents of the tank was backsiphoned into the water supply system.

The owner of the private water system stated that at least one customer drank the water, but no one became ill. However, one resident reported to the newspaper that the water caused a burning sensation in her stomach and her daughter got sores in her mouth after drinking the contaminated water.

Lab tests taken by the Chelan-Douglas Health District on May 2, showed 2,4-D at a level of 16.1 ppm. At the smelling level the 2,4-D was probably in the parts per million. The customers were requested to use as much water as possible to flush out the system.

The Withrow water system serves less than 100 customers. The system operator/owner stated that backsiphonage is a common problem in the small system due to high water demands.


1986-004

DATE OF OCCURRENCE: June, 1986

LOCATION: San Luis Obispo, California

SOURCE OF INFORMATION: County Engineering Department

San Luis Obispo County

SUMMARY: Defective operating valves on a lawn sprinkler system allowed surface water to be siphoned into the water distribution system resulting in bacteriological contamination.

DETAILS:

The bacteriological quality of the drinking water in one of the service areas of the San Luis Obispo County water system did not meet drinking water standards during the months of April and June. 1986. Investigation by the service area operators found an underground sprinkler system installed without an approved backflow prevention device. It was shown by subsequent testing that the operating valves for the sprinkler system were defective and allowed surface water to be siphoned into the main distribution system. The water supply to the sprinkler system was turned off and later tests showed the problem to be solved.

The property owner was notified that his service would remain turned off until a proper backflow prevention device was installed or the lawn sprinkler system was physically cut off from the main distribution system.

The operators of the water service area flushed and disinfected the water distribution system to restore water quality.


1986-005

DATE OF OCCURRENCE: August, 1986

LOCATION: Springfield, Oregon

SOURCE OF INFORMATION: Springfield Utility Board

SUMMARY: A home owner created a cross connection that allowed the backflow of testing dye from the residence's toilet tank during a high bill investigation.

DETAILS:

While investigating a high bill complaint, the utility service man provided the home owner fluorescent dye to be placed in the toilet tank. If a leak existed in the toilet tank, the dyed water would show up in the bowl indicating a leak that would not be visible yet would contribute to a high bill. While the home owner installed the dye in the toilet tank, the service man tuned the water off to replace the test meter and was left open when the water was turned off to replace the meter.

When the water service was restored, fluorescent dye came out of the hose indicating there had been a cross connection where the home owner had placed the dye. The home owner would not allow the service man to enter his house to inspect or check on the cross connection, however, with the help of the City Plumbing Inspector, the home owner was persuaded to install an approved toilet tank valve that provided the appropriate air gap.


1986-006

DATE OF OCCURRENCE: May, 1986

LOCATION: Springfield, Oregon

SOURCE OF INFORMATION: Springfield Utility Board

SUMMARY: A backflow of carbon dioxide from a soda dispenser was allowed by a malfunctioning ball-check valve.

DETAILS:

A local deli called just after noon to say they had considerable amounts of air in the line. They stated it was also impossible to draw soft drinks or use the water in the sinks. On arriving, the Water Department Serviceman witnessed large bursts of "air" from the kitchen sink faucet and "air" in the water samples he took. In tasting the water, he found it to have a bitter aftertaste.

Further investigation found that the carbon dioxide cylinder was almost empty and the ball-check valve had been fouled, allowing the carbon dioxide to back up into the plumbing system.

When the check valve was replaced the "air" problem was eliminated. Further investigation is taking place at this time to determine a more acceptable type of backflow device to replace the ball-check commonly installed on this type of equipment.


1986-007

DATE OF OCCURRENCE: October, 1986

LOCATION: Lacey's Chapel, Alabama

SOURCE OF INFORMATION: "Birmingham Post-Herald" Oct. 11, 1986

"The Birmingham News", Oct. 10 & 16, 1986

SUMMARY: A water main break caused the backflow of sodium hydroxide into the public water system, resulting in several customers receiving caustic chemical burns.

DETAILS:

On Wednesday, October 8, 1986 an 8-inch water main broke in Lacey's Chapel, Alabama. During the main repair one water utility workman suffered leg burns from some undetermined chemical and required medical treatment.

On Wednesday night and early Thursday, several quality complaints were received from the area of Lacey's Chapel served by the broken water main. Water service to the area was shut down at 7 a.m. Thursday and an investigation initiated.

One resident entered the shower at 5 a.m. Thursday. When he got out of the shower his body was covered with tiny red blisters. He and other Lacey's Chapel residents received medical treatment Thursday after their water supply was contaminated by sodium hydroxide, a caustic chemical. About 60 homes in the area received contaminated water.

The source of the contamination was apparently a nearby chemical company. When the water main broke on Wednesday, a truck driver was adding water to a tanker truck that had carried sodium hydroxide. Although it was normal procedure to add water from the top of the tanker, on this occasion the driver was filling the tanker from a connection at the bottom. When the driver realized that water was no longer going into the truck due to loss of pressure, he closed the valve.

The water utility flushed the water main on Thursday. health officials made sure all inside pipes were flushed, and then checked the pH level of the water. Measurements of pH were as high as 13 in some homes.

The chemical plant did not have a backflow prevention device on its water service. The water utility did not have a cross connection control program in place, although state regulations require public water systems to have a program. At the time, the city was in the process of writing an ordinance that would set up a cross connection control policy.


1986-008

DATE OF OCCURRENCE: December, 1986

LOCATION: Vancouver, British Columbia

SOURCE OF INFORMATION: Vancouver Water Department

SUMMARY: The rupture of a transmission line caused very low or negative pressure throughout a large portion of a municipal water system resulting in the backflow of both bacterial and chemical contaminants.

DETAILS:

At 2:30 a.m. on December 11, 1986 a regional water authority's 96-inch underwater crossing of Burrard Inlet ruptured. This transmission line is one of three transmission lines supplying the City of Vancouver from mountain reservoirs; two underwater crossings and one overland transmission main. At this time, the overland transmission line supplying the Vancouver region was out of service for reconstruction of a dam intake structure. The flow of water from the ruptured pipeline was 420 mgd, with approximately 100 mgd from the Vancouver side. The high flows through the one remaining transmission route resulted in low or negative water pressure (vacuum) throughout much of Vancouver's distribution system for a three hour period. The area affected included the Downtown Business District, adjoining West End highrise apartment area, and the west side residential districts. Approximately 140,000 of Vancouver's 430,000 population were without water or supplied downstream from a distribution system subjected to negative pressure (vacuum) that could permit backsiphonage of contaminants into the water supply.

The number of water quality complaints were too numerous to record. The high flows through the transmission and distribution system resulted in the water becoming dark brown in color from the disturbed iron oxide laden sediment in the predominantly cast iron distribution system. Due to the lack of staff during the emergency, individual water quality complaints could not be investigated. Typical of the complaints indicating a possible backflow incident was the "green water" complaint from commercial buildings.

Bacteriological samples collected in the late morning of December 11, following the restoration of the water pressure showed 12 out of 15 samples from areas with low or negative pressure had positive total coliform counts; two of the 12 positive samples also had positive fecal coliform counts. The source of the bacteria could have been either backsiphonage through leaks in distribution mains or through cross connection from within the distribution system or private plumbing systems.


1986-009

DATE OF OCCURRENCE: April, 1986

LOCATION: Fayetteville, North Carolina

SOURCE OF INFORMATION: Watts Regulator Company "Stop Backflow"

SUMMARY: Following a water main break, the pesticides Chlordane and Heptachlor from a tank on a pest control company truck was backsiphoned into the plumbing system of an office building and out into the municipal water system.

DETAILS:

On April 17, 1986 employees of a pest control company working at an office building in Fayetteville, North Carolina were filling one of their pesticide truck's tanks with water when a break occurred in a municipal water main. The contents of the tank being filled were backsiphoned into the building and municipal water system.

Residents in the area reported smelling an odor in their water. No illness was reported from ingesting the water.

The highest contamination level was detected in the office building: 5.5 parts per billion of the pesticide Heptachlor. The following day, water samples collected from one fire hydrant near the office building showed 0.07 and 0.04 ppb. of Chlordane and Heptachlor respectively.

After the backflow incident, the office building's water supply was shut off to prevent further contamination of the municipal system. The municipal water system was flushed. Residents in the area were warned not to use the water for human consumption if they detected an odor like gasoline. They were also urged to drain then flush their service lines and hot water tank.


1986-010

DATE OF OCCURRENCE: July 4, 1986

LOCATION: Winnipeg, Manitoba

SOURCE OF INFORMATION: Western Canada Water & Waste Association

SUMMARY: A faulty check valve on a boiler permitted the backflow of antifreeze into the potable water system.

DETAILS:

On July 4, 1986 the City of Winnipeg Backflow office was asked to investigate a cross connection at a high rise apartment block. It was discovered that a check valve protecting three heating boilers had failed. The high pressure cold water pump was found to be fluctuating and when the pressure had dropped, anti-freeze from the boilers transferred to the potable water system


1987-001

DATE OF OCCURRENCE: June,1987

LOCATION: Kitchener, Ontario

SOURCE OF INFORMATION: Kitchener-Waterloo Record

SUMMARY: Several employees of an electroplating plant were admitted to a hospital after drinking water contaminated with a nickel-based solution siphoned from a plating rinse tank.

DETAILS:

On June 14, 1987 the employees of an electroplating plant in Kitchener, Ontario noticed the water from one of the plant's drinking fountains "looked like Kool-Aid" and had a metallic taste. Because of the heat in the plant the employees were drinking a lot of water. By Friday, June 19, twenty-nine workers had reported being exposed to nickel contamination. Eleven were in the hospital, and six others were under observation by their family doctor for symptoms of nickel poisoning. Ingested nickel could harm the lungs, kidneys, liver and immune system.

The nickel solution most likely entered the plant's water system by backsiphonage through a submerged inlet (cross connection) to a plating rinse tank. On Sunday afternoon, the water system was shut down for repair work. The submerged connection was not protected by a backflow prevention assembly.


1987-002

DATE OF OCCURRENCE: August, 1987

LOCATION: Willamina, Oregon

SOURCE OF INFORMATION: State of Oregon, Health Division

SUMMARY: An employee of a plywood mill sustained minor chemical burns while washing his hands following the backflow of an alkaline cleaning compound past two unapproved single check valves into the potable water system.

DETAILS:

On August 26, 1987 a complaint was made to the State of Oregon Health Department by an employee of a plywood mill, that he had received a minor chemical burn while washing his hands.

An inspection of the plumbing arrangement in the mill revealed that a pulse pump was installed to inject a stock solution of alkaline cleaner into a potable water line feeding a manifold that supplies several wood dryers. The pump operates at 250 psi and the potable water line at 72 psi. The purpose of adding the chemical was to reduce pitch buildup in the dryer. Upstream from the point of injection were two single check valves (not an approved double check valve assembly). Upstream from the check valves was the hose the employee used to wash his hands.

Approved reduced pressure principle backflow prevention assemblies were installed on the city water supply line to the mill (8-inch and 3-inch RPBA).

The OSHA "Material Safety Data Sheet" describes the cleaner as a primary irritant that can cause serious burns to the skin, eyes and body tissues.

The mill's maintenance supervisor was notified of the incident on August 25. The potable water line in question was immediately disconnected from the system by the removal of a section of pipe.

A reduced pressure backflow prevention assembly was ordered installed in place of the two (unapproved) single check valves.


1987-003

DATE OF OCCURRENCE: April 1987

LOCATION: North Dakota

SOURCE OF INFORMATION: "Morbidity and Mortality Weekly Report"

Vol. 36; No. 36, Sept. 18, 1987

SUMMARY: Twenty-nine persons suffered ethylene glycol intoxication after drinking a beverage contaminated as a result of the backflow of anti-freeze from a heating system.

DETAILS:

On the evening of April 12, 1987 two children, four and seven years of age, were admitted to a rural North Dakota hospital because of the acute onset of marked somnolence, vomiting, and ataxia (lack of muscle coordination. After developing hematuria (blood in the urine), the children were transferred to the pediatric intensive care unit of a Fargo hospital. Urinalysis for each child revealed calcium oxalate crystals, and toxicologic studies of their urine samples revealed the presence of ethylene glycol.

On the day they became ill, both children had been at a picnic attended by approximately 400 persons at a fire hall in rural North Dakota. Of the 354 persons interviewed, 29 reported symptoms of ethylene glycol intoxication: excessive fatigue, excessive sleepiness, unsteadiness when walking, and dizziness.

One food item, a non-carbonated soft drink, was strongly associated with the intoxication. Among those who consumed the soft drink, 18 per cent became ill.

The water used to prepare the powdered beverage had been drawn from the spigot nearest the firehall's heating system. The heating system used a mixture of water and anti-freeze, and was cross connected to the potable water supply. The cross connection was regulated by a single isolating valve. It was uncertain whether the valve had been closed during the preparation of the beverage. A water sample taken at the spigot the evening of the picnic had a glycol concentration of nine percent.

Ethylene glycol is a solvent with a sweetish, acrid taste, best know for its use in anti-freeze solution. Acute poisoning from ingestion can result in central nervous system depression, vomiting, hypotension, respiratory failure, coma, convulsions, and renal damage. The fatal dose for ingestion by adults is approximately 100 grams.


1987-004

DATE OF OCCURRENCE: 1987

LOCATION: Crystal, Minnesota

SOURCE OF INFORMATION: National Environmental Health Association

Fall 1987 Newsletter

SUMMARY: The backflow of carbon dioxide from a soft drink machine into the potable water system of a restaurant caused a child to suffer acute copper toxicity.

DETAILS:

The Crystal Health Dept. received a call from a woman who had been to a restaurant in Crystal. Her two boys, ages 2 and five, had drunk water from the lobby drinking fountain which was posted "Out of Order, Do Not Drink". The five year old only took a sip of water, but the two year old drank a large quantity. Within ten minutes of drinking the water, the two year old vomited three times. The child apparently suffered from acute copper toxicity.

After being notified, the Health Department got the fountain water shut off and began an investigation. The restaurant is on the municipal water system. Employees reported that the water tasted like mineral or soda water. The off-taste had been noticed over a month before. The restaurant owner had a plumber investigate, but the plumber was unable to identify the problem.

The analysis of a water sample collected from the drinking fountain showed the following:

pH 5.6 Copper 50 ppm

Nitrate/Nitrogen 1.1 ppm Iron 0.2 ppm

Coliform Count 2.2 Psychrophiles 1.0 ppm

Standard Plate Count 1.0

The pH of the water from all other water taps in the restaurant ranged from 7.2 to 8.2.

The taste, pH and consequent high copper levels of the drinking fountain water were consistent with a backflow of carbon dioxide. Plumbing diagrams were reviewed and it was noted that the drinking fountain is the next water use appliance after the drive-up window soft drink station. The double check valves at the soft drink station were old and showed signs of deterioration and evidence of failure.

The restaurant was ordered to install an approved backflow prevention assembly.


1987-005

DATE OF OCCURRENCE: November, 1987

LOCATION: Burnaby, British Columbia

SOURCE OF INFORMATION: District of Burnaby Plumbing Branch

SUMMARY: Following the shutdown of a municipal water main to repair a break, a paperboard plant made a temporary connection between the plant's river supplied process water system and domestic water system, permitting the backflow of river water into the public water system.

DETAILS:

On November 2, 1987 a break occurred on the municipal water main supplying water to a paperboard plant and other nearby industrial properties in Burnaby, British Columbia. During the repair work, apparently polluted (dirty) water discharged from the broken main into the excavation although the isolating valves on the main were shut off.

Upon investigation, it was determined that the backflow of water was from a paperboard plant located along the Fraser River. The plant's only source of potable water, the municipal water main, was disrupted during the main repair, hence the continuous backflow of water through the plant's service connection must be from an auxiliary source of supply. The plant's service connection did not contain a backflow prevention assembly for premise isolation.

The plant maintained two water systems; a combined fire, industrial and domestic system supplied from the municipal water main, and a process system supplied from pumping water from the river. To keep the plant in operation after the water main break, a fire hose was connected between the two systems. The river water was pumped into the plant's domestic water system as well as the isolated portion of the municipal system.

The municipal work crew ordered the fire hose cross connection removed. The crew flushed and disinfected the municipal water main. The plant was ordered to immediately flush and disinfect their domestic water system and immediately install a reduced pressure backflow prevention assembly on their water service connection to provide premise isolation.


1987-006

DATE OF OCCURRENCE: December, 1987

LOCATION: Spokane, Washington

SOURCE OF INFORMATION: Spokane Water Department

SUMMARY: A large volume of air was injected into the water distribution system when mechanics attempted to clear a frozen water line with compressed air.

DETAILS:

On December 31, 1987 mechanics in a soft drink bottling plant maintenance shop connected an air line from a non-approved compressor to a potable water line in an attempt to dislodge ice which was obstructing the flow of water into the shop area. This procedure cleared the water line of ice, but a large amount of air was injected into the water distribution system surrounding the bottling plant. Complaints of air in the water from neighboring businesses resulted in Water Department maintenance crews being called on the scene to flush the mains.

During an inspection of the premises by cross connection personnel, the shop foreman indicated that the water line froze often during the winter and compressed air was used to clear the line, but isolating valves were closed before doing so and the workmen forgot to close them this time.

A reduced pressure principle backflow prevention device was ordered installed in the plant to prevent a recurrence of this problem.


1987-007

DATE OF OCCURRENCE: June, 1987

LOCATION: Fair Lawn, New Jersey

SOURCE OF INFORMATION: "Backflow Prevention" Vol 5, No 3, Mar '88

SUMMARY: Nine homes were contaminated with the pesticides Heptachlor, Chlordane and Dursban, following a water main break that allowed the chemicals to be backsiphoned into the public water system through a pest control company's service connection.

DETAILS:

On June 24, 1987 water service for 63 homes and businesses in Fair Lawn and Hawthorne, New Jersey was shut down when three chemicals were siphoned into the public water system. The backflow incident followed a water main break which occurred during the construction of a nearby bridge. At the time of the main break, an employee of a pest control company was rinsing a tanker truck with a weak solution of Heptachlor and Chlordane, and the hose he was using had Dursban on it. Between one and three gallons of pesticide entered the water distribution system.

After repair of the main, a resident reported that a milky, white substance was flowing from his kitchen faucet. The water authority immediately shut the water off again.

Sixty-three homes and businesses went without water for several days. During the water main clean-up, a water supply truck provided water for cooking and drinking. Arrangements were made to have shower facilities available at the local high school.

The pest control company assumed responsibility for the pesticide backflow incident and replaced the plumbing at nine locations where the water pipes were contaminated. At all other locations, where pipes were not replaced, testing revealed that the chemicals were non-detectable in the water.

Several residents drank the contaminated water, and watered their gardens with it. No deaths occurred from the incident. Twenty-one residents filed a $21,000,000 lawsuit against the pest control company, claiming the firm irreparably damaged plumbing fixtures, the residents continue to suffer physical distress, inconvenience and loss of property value. In addition, the plaintiffs are asking the firm to pay medical expenses incurred as a result of the incident and to set up and maintain a health surveillance program for the affected residents. The pest control company was ordered to cease and desist its operation until a backflow prevention device was installed on its service.


1987-008

DATE OF OCCURRENCE: Summer, 1987

LOCATION: Bells Rapid, Idaho

SOURCE OF INFORMATION: National Environmental Health Association

Winter 1988 Newsletter

SUMMARY: A high water demand caused the herbicide Roneet to be siphoned into a private water system.

DETAILS:

In the summer of 1987, a private water system was contaminated with the herbicide Roneet. The well supplied system was used by a number of farm families in the Bells Rapid/Hagerman area of Idaho.

The incident followed a familiar course, A tanker truck containing ten gallons of Roneet was being filled with a hose connected into a well house. As the tanker tuck was being filled, the hose became submerged in the herbicide-water mixture. The backsiphonage occurred when a water demand was placed on the system by one of the residents.

When the herbicide was discovered in the water system, the well and pressure pump were shut off. This allowed the contaminated water to enter the 1,000 gallon pressure tank. Check valves prevented herbicide from entering the well.

The water system was treated a number of times with household bleach before test results indicated that the water contained less than one part per million of the herbicide. The company that manufactured the herbicide was very cooperative and performed the testing at no charge.

On one ingested any of the contaminated water. This was due to timely notification of the few families that utilized the well. Fortunately, Roneet has an L.D. 50 of 200 to 4000 mg/kg and is not extremely toxic.

The person responsible for contaminating the well system did not own the well; he was just borrowing some water.


1987-009

DATE OF OCCURRENCE: April, 1987

LOCATION: Salem, Oregon

SOURCE OF INFORMATION: City of Salem

SUMMARY: A complaint of dirty, metallic tasting water and air in the lines followed the failure of a ball check valve on a soft drink dispensing machine that utilized a CO2 cylinder.

DETAILS:

On April 18, 1987 the City of Salem received a complaint from a coffee shop of brownish, metallic tasting water and air in the line.

Water samples taken within the building in response to the complaint showed a pH of 4.6. A control sample taken from a nearby service showed a pH of 6.8, normal for the city's water. The bitter metallic taste, coupled with the low pH os typical of a CO2 backflow incident.

The building's soft drink machine was supplied with CO2 from a 800 psi cylinder, regulated to 85 psi at the water connection. The soft drink machine had a stainless steel ball check valve to separate the carbonated water from the domestic water supply.

The soft drink supplier serviced the machine and found that debris had passed the strainer and was fouling the ball check valve.


1987-010

DATE OF OCCURRENCE: June, 1987

LOCATION: Gridley, Kansas

SOURCE OF INFORMATION: "The Gridley Gleam", Vol 5, No. 6

SUMMARY: The water supply to ten residences and one business were contaminated with the herbicide Lexon DF as a result of backsiphonage caused by a water main break.

DETAILS:

On June 20, 1987 a resident of Gridley, Kansas returned home after several days absence and noticed a chemical smell when filling the washing machine. City officials concluded that the problem was caused by "sludge in the pipes" that had been flushed out when the water came back on and recommended that the pipes be flushed for a couple of hours.

On July 1, the resident complained that there was still a problem and that the grass had died where it was watered. City officials then contacted the State Department of Health and Environment.

The State officials took water samples to determine if there may have been chemical contamination. It was concluded that some water mains were contaminated with a herbicide, later identified as Lexon DF, following the break in a water main on June 17. A tank at a nearby feed store which had contained the herbicide was being filled with water at the time of the water main break and some of the contents of the tank were siphoned into the water main.

The State officials warned the ten residences and one business supplied by the water main not to use the water for cooking or drinking until test results showed the water was safe. They also noted that if herbicide was present in the water, boiling the water would not destroy it.


1987-011

DATE OF OCCURRENCE: October, 1987

LOCATION: Gainsville, Florida

SOURCE OF INFORMATION: "The Alligator", Campus Communications

Vol. 81, No. 28 and USC FCCCHR

SUMMARY: Chemically treated water from an air conditioning unit was detected in drinking fountains in two buildings on a university campus.

DETAILS:

On September 30, 1987 chemically treated water from an air conditioning unit was detected in drinking fountains in two buildings on the campus of the University of Florida. Staff at the building housing a laser lab reported that someone connected pipes improperly while installing new equipment in the lab. The yellow-tinted cooling water then mixed with the potable water supply.

"DON'T DRINK, BAD WATER" and "DO NOT DRINK HERE, YELLOW WATER" signs were posted throughout the two buildings. Workers capped the source of the bad water and taped fountains and faucets into the "on" position to purge the system. Physical plant employees spent up to 20 hours flushing the system before removing the warning signs.

One student who drank the water stated that it tasted like "Prestone Two anti-freeze".

The method of backflow of the cooling system water was not reported. No cases of sickness were reported.


1987-012

DATE OF OCCURRENCE: May, 1987

LOCATION: Evanston, Illinois

SOURCE OF INFORMATION: "The Chicago Tribune", May 17, 1987

and USC FCCCHR

SUMMARY: The water system in a 550 bed hospital became contaminated when water from the hospital's water cooled air conditioning system "seeped" through a valve linking the two systems.

DETAILS:

On Friday, May 17, 1987 patients and workers at a 550 bed hospital in Evanston, Illinois noticed their tap water had a "foul smell and funny taste" like rust. They were told not to drink the water. Hospital officials notified the Illinois Department of Public Health.

No patients or workers had reported ill as of Saturday night. After 24 hours tests deemed the water safe for drinking.

Hospital officials suspected the water system became contaminated when water from the hospital's water-cooled air conditioning system "seeped" through a valve linking the two systems. The cause of the backflow incident was not reported.

About 2,000 gallon bottles of drinking water were delivered to the hospital. Because the hospital was able get so many bottles of drinking water. Hospital officials stated that there were no major problems.


1987-013

DATE OF OCCURRENCE: March, 1987

LOCATION: Edmonton, Alberta

SOURCE OF INFORMATION: Western Canada Water & Waste Association

SUMMARY: A faulty single hard seated check valve on a water line supplying boilers in a high rise building causes hot water to come out of cold water taps.

DETAILS:

In March, 1987 a maintenance company's service man contacted the department expressing concern over hot water coming out of cold water taps in certain areas of the high rise apartment he was servicing. An investigation of the water system traced the problem back to a faulty single hard seated check valve in the water line supplying the boilers. Apparently, the previous maintenance contractor had trouble keeping chemicals in the heating system, but instead of determining the cause, they simply added more chemicals.

There were no reported cases of anyone becoming ill. However, since the chemicals had been injected into the drinking water system for quite some time, one wonders how those chemicals affected the long term health of the tenants.

The single check valve was replaced with a reduced pressure principle backflow prevention device.


1987-014

DATE OF OCCURRENCE: August, 1987

LOCATION: Edmonton, Alberta

SOURCE OF INFORMATION: Western Canada Water & Waste Association

SUMMARY: Failure of a dual check valve on a soft drink dispenser allowed carbon dioxide to enter the water system.

DETAILS:

In August, 1987 the staff at one of Edmonton's recreational parks called the water department complaining that one of their customers had taken a drink from a drinking fountain and complained of caustic tasting water which caused a burning sensation in his throat. The inspector, dispatched to the site, noticed blue stains in some of the concession stand equipment and air in the water lines. Further investigation found that the soft drink carbonator dual check valve had failed allowing the carbon dioxide to enter the water system.

Water lines in the facility were flushed and a stainless steel dual check valve with atmospheric port was installed to replace the faulty device.


1987-015

DATE OF OCCURRENCE: January, 1987

LOCATION: University of Michigan

SOURCE OF INFORMATION: Drinking Water & Backflow Prevention

Volume 11, Number 4


SUMMARY: Four people at a university residence hall became ill after drinking soda pop from a dispenser. Possible presence of copper-containing sediment in water mix tank.

DETAILS:

Four food service employees at a residence hall at the University of Michigan, became ill on January 7, 1987, after drinking soda pop from a dispenser. They were taken to the hospital complaining of bloating, nausea, headache, dizziness and dry vomiting. All of those ill reported that the soda pop had an unusual taste, some reported a sludge-like sediment in their glass.

A service representative disassembled various parts of the machine for inspection, including visually inspecting both check valves, visually inspecting the 100-mesh y-strainer in the water line, also a new rubber seal installed on the diffuser two days earlier was inspected. All appeared to be in excellent condition. New check valves were installed as a precaution.

Green particles, possibly oxidized copper, were found in the bottom of the CO2 water mix tank, the tank was thoroughly flushed.

Samples taken from the dispenser before cleaning and inspection had 24 ppm copper. Sample taken after cleaning showed 0.11 ppm copper. The background water sample showed 0.01 ppm.

The apparent cause of this outbreak was the presence of copper-containing sediment in the CO2 water mix tank. The dispenser is standard design and well maintained, it is not known how the sediment reached the tank, a factor may be the age of the water system in the university building, old water lines have more scale and sediment than new water lines, and require more repairs, which can add to the presence and movement of copper particles within the lines.


1987-016

DATE OF OCCURRENCE: December, 1987

LOCATION: Calgary, Alberta

SOURCE OF INFORMATION: Western Canada Water & Wastewater Assoc.

SUMMARY: A water main break forces chemically treated water into an elementary school's potable water system.

DETAILS:

On December 11, 1987 the City of Calgary experienced a water main break that interrupted the water supply to an elementary school.

During the water main break a backflow condition occurred and backpressure from a hot water heating system forced chemically treated water into the school's potable water service supply. When the water main was repaired and the water pressure restored, the chemically treated water was forced into the school's distribution system, supplying contaminated water to drinking fountains and washrooms. These contaminants showed up in water samples routinely taken after a water main break. The laboratory identified these contaminants as chromates, a very highly toxic chemical compound.

Fortunately, the children were sent home at the time of the water main break and did not drink any of the contaminated water. The school remained closed for several days while the school's water distribution system was flushed, sampled and re-flushed until water samples revealed no chemical traces. Backflow protection was requested by the inspector, and was installed on the water supply to the heating system.


1988-001

DATE OF OCCURRENCE: May, 1988

LOCATION: Edgewater, Florida

SOURCE OF INFORMATION: The Orlando Sentinel, May 1, 1988

SUMMARY: The malfunction of a valve at a paint factory resulted in the backflow of propylene glycol into the factory's potable water system.

DETAILS:

On April 29, 1988 the City of Edgewater notified its 5,700 water customers not to use tap water for drinking, cooking or bathing because of a chemical contamination of the water system.

The chemical contaminant was propylene glycol. Propylene glycol can irritate the eyes and skin on contact. Although it is relatively non-toxic, it may cause heart and urological damage if consumed in large doses.

The chemical was used at a local paint factory to keep paint from breaking down after being exposed to weather. The contamination occurred when a valve malfunctioned at the paint factory, causing the chemical to flow into the potable water system. The pressure at the plant was higher than the city's water system, permitting the backflow incident to occur. Because the plant was about 12 years old, the plant's plumbing system did not comply with the current plumbing code requirements for backflow prevention.

Although the contamination occurred on Thursday afternoon, it was not reported until Friday afternoon. The plant's production manager thought the contaminant was confined to the plant. He shut off the plant's water connection to the city water system and flushed the plant's system. The Florida Department of Environment Regulation ordered the ban on water usage throughout the city as a precaution. Tests on samples collected Friday from the city water system did not show the presence of propylene glycol. No one sought medical aid from the local hospitals for an illness related to the consumption of contaminated water.

A double check valve assembly was ordered installed on the plant's water service connection.


1988-002

DATE OF OCCURRENCE: March, 1988

LOCATION: Cleveland, Ohio

SOURCE OF INFORMATION: Cleveland Plain Dealer, March 9, 1988

and Backflow Prevention, May 1988

SUMMARY: The backflow of a dilute water soluble oil containing toxic chemical additives contaminated the public water main and six house supplied from the main.

DETAILS:

On Friday, March 4, 1988 the backflow of a dilute water soluble oil containing toxic chemical additives contaminated a Cleveland, Ohio water main and six houses supplied from the main.

The oil, used for cooling equipment, was mixed with water stored in a tank at a local manufacturing plant. The chemical additives, used to prevent growth of bacteria, were nitro-butyl morpholine and ethylniotro trimethylene. The mixture is toxic in concentrated form.

A single check valve on the water line to the storage tank malfunctioned after the tank was pressurized, allowing the oil-water mixture to flow into the city water mains.

City employees took water samples from the distribution system on Saturday after receiving complaints from residents of foul smelling water. An official warning was issued as soon as the city determined by sight and smell that there might be a water quality problem. The city flushed the neighborhood fire hydrant on Saturday.

Most of the residents of the area of the manufacturing plant stopped drinking the water when the smell and taste started bothering them on Friday. One resident reported drinking the water caused him to vomit. Two families that stated they were not warned to not drink the water, consumed the water until Monday. One family reported that their children were feeling nauseous.


1988-003

DATE OF OCCURRENCE: August, 1988

LOCATION: Fresno, California

SOURCE OF INFORMATION: "The Fresno Bee". September, 1988

and Febco Inc..

SUMMARY: The inappropriate application of a backflow prevention assembly resulted in the backflow of a caustic chemical into an elementary school's potable water system.

DETAILS:

The Fresno Unified District replaced 63 backflow prevention assemblies on heating and cooling systems throughout the school district after one backflow prevention assembly failed to prevent the backflow of a caustic chemical in an air conditioning system from entering the school's potable water system.

On August 11, 1988 the city water system supplying the Fremont Elementary School lost pressure. Soon after, a teacher noticed that the water had a pink tint. The chemical added to the chiller water to prevent mineral buildup in the piping was sodium nitrite. Sodium nitrite is a highly caustic chemical that could cause burns or other irritation. The teachers did not allow the children to consume the water; no illnesses were reported.

The backflow assembly was a pressure vacuum breaker. Its application on the heating and cooling systems inappropriate, since backpressure could occur. After the backflow incident, the School District replaced them with reduced pressure principle assemblies.


1988-004

DATE OF OCCURRENCE: November, 1988

LOCATION: Victoria, British Columbia

SOURCE OF INFORMATION: Victoria Water Department

SUMMARY: A naval dockyard's domestic water system was contaminated with saltwater, pumped from a ship's fire protection system into a dockside fire hydrant.

DETAILS:

On Sunday, November 6, 1988 a naval ship tied up to a jetty in the government dockyard and connected its fire protection system to a fire hydrant. This connection to the fire hydrant would not have occurred under normal conditions. The ship had six fire pumps on board, but three of the pumps were malfunctioning at the time. When the fourth pump stopped operating, the ship's officers became concerned, and connected the ship's fire protection system to the dockside fire hydrant to augment their system.

It was assumed that the dockside fire protection system was a saltwater system. Unfortunately, it was a combined domestic and fire protection system. When the pressure in the ship's system increased after connection to the fire hydrant, it was believed that the pressure from the dockside system would stay high. In fact, the connection was made late at night when the domestic supply pressure was at its highest. With the increased demand on the system during the day, the supply pressure dropped. The higher pressure in the ship's (saltwater) fire protection system forced the non-potable sea water into the dockyard's domestic water system.

Tests using silver nitrate indicated that the contamination was quite extensive, almost to the dockyard service connection to the municipal water system. Backflow protection assemblies were not present on either the dockside hydrants or the service connections to the municipal water system.

To remove the saltwater and the accompanying bacterial contaminants, the dockyard water system was flushed and a chlorination system, borrowed from a swimming pool, was installed to inject 6 ppm chlorine to disinfect the system. The chlorination continued until November 12th.


1988-005

DATE OF OCCURRENCE: March, 1988

LOCATION: Eugene, Oregon

SOURCE OF INFORMATION: Eugene Water and Electric Board

SUMMARY: The backflow of water from a chemically treated boiler occurred as a result of the failure of an unapproved backflow prevention assembly consisting of two check valves.

DETAILS:

On March 31, 1988 superheated water from a boiler located in a tire retread plant flowed into the plant's domestic water system then into the water service connection to the water main on the street. The hot water broke (melted) the 2-inch PVC water service pipe and damaged the water distribution main. The boiler water contained an unidentified boiler treatment compound.

The cold water feed line to the boiler had an unapproved backflow prevention assembly consisting of two single check valves. Both check valves failed, allowing the back-pressure backflow incident to occur. No backflow prevention assembly was installed on the service connection to isolate the premise.

The water utility ordered the immediate installation of a reduced pressure backflow assembly at the meter on the water service connection to isolate the premise.


1988-006

DATE OF OCCURRENCE: September, 1988

LOCATION: Anchorage, Alaska

SOURCE OF INFORMATION: Denali Towers/Stone-Drew Assoc.

SUMMARY: The backflow of glycol through a faulty single check valve on a fire sprinkler system resulted in "brown and smelly" water occurring in a high rise building.

DETAILS:

On September 7, 1988 a number of tenants in a high rise building reported "brown and smelly" water in the potable water supply. Several tenants took samples to the municipality. It was thought that the complaint was the result of water sitting and collecting sediment on the three day Labor Day weekend. The plumbing system was flushed and the problem appeared to have been solved.

The next morning, the building again experienced foul smelling water. Several people mentioned that the smell was similar to glycol. Water samples were collected for laboratory analysis. "Do Not Drink" signs were posted on all drinking fountains.

The source of the contamination proved to be the backflow from one section of the pressurized (wet) fire sprinkler system in which a single check valve had failed. The system had a slight glycol residue from the original construction period.

The building code required that fire sprinkler lines supplied by municipal water mains be equipped with backflow prevention assemblies. This building was not so equipped. The municipality stated that this code requirement was in effect in 1979 when the building was constructed, but enforcement was lax and a number of buildings were erected without backflow prevention on the fire sprinkler system.

On September 12, an approved backflow prevention assembly was installed on the fire sprinkler system.


1988-007

DATE OF OCCURRENCE: September, 1988

LOCATION: DeKalb County, Georgia

SOURCE OF INFORMATION: "Georgia Epidemiology Report, Vol 5, No 1

SUMMARY: The absence of a backflow preventer on a boiler resulted in the backflow of ethylene glycol into a school's potable water system.

DETAILS:

On the morning of September 9, 1988 a maintenance worker at an elementary school in DeKalb County, Georgia detected an odor similar to antifreeze in the water supply in the kitchen. The maintenance supervisor and local health department staff suspected a problem with a cross connection to the boiler. Instructions were given immediately to disconnect all drinking fountains in the school and cease preparation of lunches for the children.

Water samples were collected at the hot water heater and in the kitchen, and the entire water system was flushed for a period of three hours. Following flushing, a second group of samples were collected. All samples were tested for the presence of ethylene glycol.

The source of the problem was readily identified as the absence of a backflow preventer on the water line between the hot water heater and the boiler. The bypass valve to the boiler had been left open and water demand elsewhere in the building created enough of a pressure differential to allow ethylene glycol from the boiler to backflow into the potable water line.

Laboratory analysis confirmed the presence of ethylene glycol. Although there is no standard for permissible concentration of ethylene glycol in drinking water, evaluation of occupational exposure standards resulted in determination of less than 1 ppm as the level at which the water could be considered safe. Over the three hour period of flushing, a reduction in concentration was demonstrated from 6 to 4 ppm at the hot water heater, and 3 to 1 ppm at the cold water tap in the kitchen. Due to these unsatisfactory results, 24 hours of flushing was initiated on September 12, 1988.

A similar incident occurred in the county in 1983. Due to the occurrence of two similar incidents in schools, the county recommended the inspection of all boiler rooms in schools, the installation of backflow preventers on all boilers, and the elimination of any bypass lines.


1988-008

DATE OF OCCURRENCE: December, 1988

LOCATION: Garland, Texas

SOURCE OF INFORMATION: Watts Regulator Company "Stop Backflow"

"Garland Daily News", January 7, 1989

SUMMARY: Twelve children suffered from copper poisoning after drinking water contaminated from a soft drink dispensing machine.

DETAILS:

A dozen children attending a special show at a theater on December 31, 1988 suffered copper poisoning after drinking water and soft drinks. The twelve children were part of a group of 161 from local day-care centers.

A backflow preventer on a mixing head attached to a soft drink tank malfunctioned on December 30. Employees shut the soft drink tap off when the malfunction occurred, but they did not realize the nature of the malfunction and began using the machine again the next day. After the backflow of carbon dioxide, carbonated water remained in the copper piping overnight and leached copper from the pipe. The next day, copper salts were carried in the water to the drinking fountain about 15 feet away and then to the soft drink dispensers. The first children to drink the copper contaminated water became ill, suffering from severe vomiting and cramps.

When the first children began vomiting, the quick actions of the theater manager prevented the other children from having anything to drink.

The water department flushed the potable water lines.


1988-009

DATE OF OCCURRENCE: November, 1988

LOCATION: Raytown, Missouri

SOURCE OF INFORMATION: "Kansas City Times" and "ABPA News"

SUMMARY: The failure of a backflow prevention assembly resulted in the contamination of a school's drinking water by water from a boiler that contained a chromium based corrosion inhibitor.

DETAILS:

Sixty-four students and teachers at a vocational-technical school were sent to an area hospital for tests after a corrosion inhibitor was detected in the school's drinking water. Blood and urine tests were given to check for traces of chromium, a chemical that in large doses can cause kidney and liver damage. A hospital spokesman reported that none of those examined appeared to have drunk enough of the contaminated water to cause any problems.

The contamination appeared to have occurred when a backflow prevention assembly failed at the building's furnace, allowing boiler water to enter the drinking water supply.

Students were told about 9:30 a.m. not to drink the water. The campus was closed for the day. Water samples collected in the afternoon showed that the contamination appeared to have been flushed from the system.

POSTSCRIPT:

Additional information indicates that a backflow prevention assembly was not installed at the time of the incident. [Information courtesy of BAVCO]


1988-010

DATE OF OCCURRENCE: September, 1988

LOCATION: Edmonton, Alberta

SOURCE OF INFORMATION: Western Canada Water & Waste Association

SUMMARY: A faulty wafer check valve permitted the backflow of water from a fire sprinkler system into an office building's potable water system.

DETAILS:

In September, 1988 occupants of a high rise office building in Edmonton, Alberta complained of brown water flowing from the faucets throughout the building.

The Cross Connection Control Inspector found the domestic water pump had been taken out of service for repairs. The piping between the fire system and the domestic water supply was arranged in such a way that it allowed either pump to serve both systems when a bypass valve was turned on. A single wafer check valve failed to contain the contaminants in the fire system; as a result, the fire system contaminated the domestic water supply.

The inspector recommended that the system be separated and a double check valve assembly be installed in water lines serving the fire systems and the high rise's domestic cold water supply.


1988-011

DATE OF OCCURRENCE: August, 1988

LOCATION: Gilbert, Arizona

SOURCE OF INFORMATION: "Mesa Tribune" and "Backflow Prevention"

SUMMARY: An interconnection between an irrigation system and a decorative pond may have resulted in non-potable water being pumped into the public water system.

DETAILS:

On August 25, 1988 it was discovered that a water meter supplying an irrigation system near a decorative lake in an industrial park was running backwards, indicating that water was backflowing into the public water system.

The water in the man made lake was pumped into an irrigation system that watered a landscaped area along a public road. The irrigation system was initially being supplied by the public water system. When a pump was installed to supply the irrigation system, the backflow occurred.


1988-012

DATE OF OCCURRENCE: April, 1988

LOCATION: Salt Lake City, Utah

SOURCE OF INFORMATION: Dept. of Public Utilities,

Salt Lake City, Utah

SUMMARY: The apparent failure of a reduced pressure principle assembly resulted in a cleaning solution backflowing into a building water system.

DETAILS:

On April 18, 1988 a maintenance man was performing a regular chemical cleaning treatment of a "closed water system". The domestic water system supplying the closed system was protected by a 3/4-inch reduced pressure principle backflow prevention assembly. Shortly after the cleaning began, the maintenance man received a complaint that the water had a funny taste. Upon investigation, the water was found to have a pink tint. A water sample was collected, and the entire water system in the building was shut down.

The supplier of the cleaning chemical stated that the chemical only needed to be flushed from the system. To drain and flush that water system, the RPBA assembly was removed.

The RPBA assembly was not tested following the backflow incident. The RPBA assembly was last tested the previous June. Test records indicated that the assembly was repaired three times in the last six years.

The maintenance man installed a new RPBA assembly after flushing the system.

POSTSCRIPT:

Subsequent information indicated that the check valves and relief valve were plugged with a very fine rust. The rust was so well packed that it held the relief valve closed. The assembly may not have been maintained even though the records indicated the assembly was repaired. [Information courtesy of BAVCO]


1988-013

DATE OF OCCURRENCE: April, 1988

LOCATION: Edmonton, Alberta

SOURCE OF INFORMATION: Western Canada Water & Waste Association

SUMMARY: A water main break caused cleaning solution in a toilet tank to backflow into the residence potable water system.

DETAILS:

A home owner called the Cross Connection Control Office wondering why he had blue water coming out of his taps. The inspector sent to investigate found that there had been a water main break in the area where the complaint was registered. An inspection of the residence found the toilet tank had a cleaning dispenser in it and the ballcock was below the water level. When the water in the street was turned off to repair the leak a vacuum was created. The ballcock did not have an anti syphon feature and allowed the water from the tank to be syphoned back into the water system. When the water was turned back on the blue color from the toilet bowl cleanser alerted the owner of the problem. An anti-syphon ballcock was installed so that its critical level was 25mm above the overflow tube solved any future contamination problems from this toilet tank.


1988-014

DATE OF OCCURRENCE: August, 1988

LOCATION: Edmonton, Alberta

SOURCE OF INFORMATION: Western Canada Water & Waste Association

SUMMARY: Failure of single hard seated check valve allowed water from the heating and chilled water system to enter the potable water system in a shopping mall.

DETAILS:

Patrons & staff in one of the larger stores in a shopping center noticed that water in the cafeteria and washrooms was murky. Investigations by the inspector found that a water line in the vicinity had broken disrupting the water supply to parts of the shopping mall. An inspection of the water system within the building found that a single hard seated check valve had failed allowing water from the heating and chilled water system to enter the potable water system.

The owners were instructed not to use the water until all the lines were properly flushed and water samples confirmed the water was safe to drink. In addition, a reduced pressure principle backflow preventer was installed in the water line serving the heating and cooling system.


1988-015

DATE OF OCCURRENCE: June, 1988

LOCATION: Bella Glade, Florida

SOURCE OF INFORMATION: "The Gainesville Sun" June 26, 1988

"Tampa Tribune" June 25, 1988

SUMMARY: A man died of an insecticide intoxication after drinking water from a bottle filled with contaminated water from a faucet at an airstrip.

DETAILS:

A city worker who died a day after cutting grass near an airstrip was killed by pesticides, but officials aren't sure how the poison got into a bottle of water the man sipped from as he worked.

The man got off his riding mower near the grass airstrip to fill his bottle from a faucet. He drank the water and continued working, but then fell ill and went to the hospital, where he died the next morning.

The Chief Medical Examiner's report shows "Complications due to insecticide intoxication and chronic alcoholism" killed the man. The report also shows his blood-alcohol level as 0.23 percent.

Water from the faucet used to fill the bottle is often used to dilute pesticides that are pumped into crop dusting planes, and officials speculate that insecticides had been sucked into the water line. Samples taken later from the faucet did not show any trace of pesticide.


1988-016

DATE OF OCCURRENCE: November, 1988

LOCATION: Cave Creek, Arizona

SOURCE OF INFORMATION: Phoenix Gazette, Nov. 2, 1988

SUMMARY: Illegal private wells are suspected as source of contamination of arsenic in the city water supply.

DETAILS:

Health officials , puzzled by high levels of arsenic in the Cave Creek water supply, advised anyone with illegal private wells to disconnect them from the home and use that water for purposes other than drinking and cooking.

Authorities believe that source of the poisoning may be illegal wells contaminating the system. Through a cross connection, water from private wells in homes also hooked up to the Cave Creek Water Co.'s municipal system could infiltrate the city's supply.

The municipal water system cannot manufacture arsenic, it is suspected that the arsenic usually leaches into a well from naturally occurring deposits found in rock formations and soil.

The arsenic levels in the Cave Creek supply are dangerous only if ingested over a 20 to 40 year period. State law sets the maximum contaminant level for the poison at 0.05 mg/l. Cave Creek's water samples averaged 0.072 mg/l.


1988-017

DATE OF OCCURRENCE: August, 1988

LOCATION: West Jordan, Utah

SOURCE OF INFORMATION: "Deseret News" August 21, 1988

SUMMARY: At least five subdivisions have dual water systems for culinary and irrigation water creating possible cross connection health hazards.

DETAILS:

On a July holiday weekend, the City of West Jordan, Utah, received a call about a cross connection in a subdivision where homeowners have a dual irrigation and potable water system. A caller noted the water was cloudy. The Water Utility put the subdivision on a Boil Water order. The City then flushed all the culinary water lines through fire hydrants until test samples were clear, then the Boil Water order was removed but the whole irrigation system was down for an additional four days.

At least five West Jordan subdivisions have pressurized irrigation systems that allow homeowners to use inexpensive irrigation water outdoors rather than using more expensive treated drinking water. But health problems can result when lines are cross connected and a pressure imbalance draws raw water into culinary lines.

The City Council voted unanimously to approve an ordinance that allows the City Manager to shut off all water service to a house that interconnects potable and non-potable water systems until the irrigation system is permanently disconnected, in addition, the penalties for cross connecting culinary and irrigation water lines in West Jordan have been increased to lessen the risk of a health hazard.

The new provision that prohibits cross connections also requires property owners with dual systems to make distinctive color markings on all exposed portions of the non-potable water systems, install potable and non-potable lines in separate trenches, place key valves on all hydrants and sprinkler controls so that they can't be operated by non-authorized users and keep all non-potable systems outside buildings except greenhouses and plant and animal production buildings.


1989-001

DATE OF OCCURRENCE: February, 1989

LOCATION: Keizer, Oregon

SOURCE OF INFORMATION: City of Keizer Water Department

SUMMARY: The cross connection of a cooling tower reservoir resulted in the supply of non-potable water to an ice making machine, produce hoses and the employee lunch room in a super market.

DETAILS:

On February 8, 1989 the Keizer Water Department received a call from a local plumber stating that after he had turned off a super market's water service at the meter to make repairs to the plumbing system, the plumbing system remained pressurized. A Water Department employee responded to the site and confirmed that the correct water meter had been turned off, since two metered connections served two separate parts of the building.

A trace of the water piping revealed that the water system was directly connected to a compressor normally supplied by a cooling tower. This cross connection was made to the compressor in the event that the water from the cooling tower was unable to cool the compressor. A check of the cooling tower reservoir showed that the water level had dropped, and was continuing to drop until another valve at the compressor was closed.

The water from the cooling tower contaminated the plumbing system supplying the super market's ice making machine, hose bibs in the produce department and sinks in the employee lunch room.

The cross connection supplying backup water to the compressor/ cooling tower was ordered disconnected. An air gap was ordered installed in the water pipe supplying the cooling tower reservoir.


1989-002

DATE OF OCCURRENCE: February, 1989

LOCATION: Seattle, Washington

SOURCE OF INFORMATION: Seattle Post Intelligencer, Vol 126, No 41

SUMMARY: About two dozen toilets and urinals in the County Courthouse "exploded" when they were flushed, after an air compressor was connected to the building's water system.

DETAILS:

Starting about 11:30 a.m. on February 16, 1989 the flushing of toilets and urinals in the King County Courthouse Building resulted in "geysers" erupting. No one admitted being hurt by the unusual blasts, although several people were apparently badly drenched, or very surprised.

The source of the air in the plumbing system was the errant connection, by construction workers building a bus tunnel, of an air compressor to a hose bib on the building's water system.

In addition to soaking several people, the blast of air broke between 20 and 25 porcelain toilets bowls and urinals.

After the incident, all restrooms in the 10-story courthouse were closed for the day and employees had to walk across the street to the county administration building to use the restrooms. Because of the possibility of contamination, drinking water was turned off.


1989-003

DATE OF OCCURRENCE: June, 1989

LOCATION: Redmond, Oregon

SOURCE OF INFORMATION: Oregon Health Department

SUMMARY: Eight employees of a high school reported becoming ill after the backflow of ethylene glycol occurred from the school's air conditioning system.

DETAILS:

On the morning of June 9, 1989 the City of Redmond, Oregon called the Oregon Health Division to report a backflow incident that happened at a high school. The central air conditioning system had built up pressure and pushed coolant back into the school's drinking water supply.

Fortunately, school was out on June 8, for summer break. However, eight employees that drank water from the teacher's lounge reported feeling ill that afternoon and were sent to the hospital.

Once the problem was discovered, the air conditioning system was shut down and drained, and the school was isolated from the rest of the water system. The city was instructed to collect water samples and then begin flushing the school's water lines.

The water samples were analyzed that evening. Ethylene glycol was detected in the school water system and also out in the city water distribution system. The water sample taken at the teacher's lounge, the closest point to the cross connection, contained 9,600 ppm of ethylene glycol.

Based on the information that ethylene glycol is easily removed from a water system through vigorous flushing of water lines, the school officials were instructed locate every water line and flush it. Also to turn off all drinking water fountains, post "DO NOT DRINK" notices, and supply bottled water until further notice from the Oregon Health Division. Once the entire system had been flushed, they could take down the notice and turn on drinking fountains.

The backflow occurred at the connection between the plumbing system and the air conditioning system which was only separated by a pressure reducing valve. About 18-inches upstream from the pressure reducing valve was the connection to the teacher's lounge.

The school was required to install a reduced pressure backflow prevention assembly on the water connection to the air conditioning system.


1989-004

DATE OF OCCURRENCE: July, 1989

LOCATION: Kennewick, Washington

SOURCE OF INFORMATION: City of Kennewick

SUMMARY: The failure of a single check valve and pressure regulator resulted in the backflow of soapy water from a carpet cleaning truck into a homeowner's hot water tank.

DETAILS:

On July 14, 1989, the City of Kennewick Water Department received a complaint of "soapy water".

The homeowner informed the Water Department that a carpet cleaning and dye company had cleaned some carpeting in the house and connected to the outside hose bib for water to supply the truck.

The cleaning equipment included an in-line single check valve and pressure regulator on the supply line. Both failed, causing the backflow of a "low sudser soap" solution into the homeowner's hot water heater. The contamination was confined to the water heater. The water heater was flushed for 90 minutes and a health sample taken.

The carpet cleaning company was required to permanently install a reduced pressure backflow assembly on the water supply line to the truck.


1989-005

DATE OF OCCURRENCE: July, 1989

LOCATION: Cincinnati, Ohio

SOURCE OF INFORMATION: "The Cincinnati Enquirer" July 29, 1989

Stone-Drew/FEBCO

SUMMARY: The backflow of an algae-retarding chemical into the drinking water system of a government office building apparently caused at least 12 illnesses.

DETAILS:

On July 27, 1989 an algae-retarding chemical detected in the drinking water system of a government office building apparently caused 12 illnesses. The Health Commissioner stated that anyone who drank from fountains in the building on July 27 or 28, 1989 could become ill with diarrhea or vomiting, especially after drinking alcoholic beverages. The potential illness was not long-term or life-threatening.

On July 27, 1989 the Health Commissioners office received reports of "blue water" from the office building. An investigation found that the reason for the complaints was a blue liquid, known commercially as Acid Blue 9, used to prevent algae in the condenser of the building's air-conditioning system.

The cross connection existed between the air-conditioning and potable water systems. The backflow of the chemical occurred while crews were working on the air-conditioning system.

About 1,000 employees worked in the building, and several hundred visitors could have passed through the building on the day the contaminant was detected.


1989-006

DATE OF OCCURRENCE: October, 1989

LOCATION: Kennewick, Washington

SOURCE OF INFORMATION: City of Kennewick,

Washington Department of Health

SUMMARY: A "dirty, black water" complaint alerted the water purveyor to the cross connection of seven water softeners to the sewer line.

DETAILS:

On October 4, 1989 the City of Kennewick Water Department received a complaint from a customer concerning "dirty, black water". The water department cross connection specialist investigating the complaint determined that the "dirty water" incident was confined to the customer's house.

A water softener was found in a closet off the family room. The discharge hose was inserted approximately 4-inches into the sewer line. The black "gunk" found at the end of the discharge hose was recognized by the homeowner as being like the black stuff that came out of the bath tub faucet.

The distributor for the water softener stated that installation of the softeners is done by independent contractors. The distributor could only provide a list of softener sales for the last two years. Of the nineteen units sold, six units were sold to other customers in Kennewick.

An inspection was made of these six units. All were cross connected to a sewer line. At one location the homeowner reported "dirty yellow smelly water" had occurred in June of 1989.

All of the water softeners inspected were by-passed until their discharge pipe was isolated with an approved air gap.


1989-007

DATE OF OCCURRENCE: June, 1989

LOCATION: Victoria, British Columbia

SOURCE OF INFORMATION: City of Victoria, Engineering Dept.

SUMMARY: Following a shutdown of a water main for maintenance, a machine coolant was backsiphoned into the potable water piping in a manufacturing plant.

DETAILS:

On June 12, 1989 the water department shut down a block of water main for repair work. All businesses on the block were advised that the shutdown would take place from 11:00 p.m. to 2:00 a.m. the following day. On June 13, an employee of a manufacturing company on the block took a drink of water from a fountain and immediately vomited. The water was a dark green color and had a bitter taste.

A cross connection inspection revealed a tap with a hose leading into a tank containing a mixture of water and machine coolant. Tests of the drinking water indicated that the water contained a high level of copper and (likely) the coolant. It was assumed the tap was open during the period the water was shutoff, resulting in the backsiphonage of the contaminant into the potable water system. The pink color coolant, after sitting in the plumbing system for several hours, had reacted with the copper piping, causing the water to turn a dark green color.


1989-008

DATE OF OCCURRENCE: May, 1989

LOCATION: Edmonton, Alberta

SOURCE OF INFORMATION: Western Canada Water & Waste Association

SUMMARY: The backflow of water through an alarm check valve on a fire system resulted in the contamination of the water supply in a department store.

DETAILS:

In May, 1989 occupants of a department store in one of Edmonton's shopping malls complained of brown water coming out of the faucets throughout the store.

The Cross Connection Control Inspector found that the alarm check valve, in the fire system, had gone off on several occasions when the City water pressure had been disrupted.

Water samples indicated turbidity and iron content higher than acceptable drinking water standards. Water samples from neighboring stores were normal.

The owner of the building was asked to install a D.C.V.A. in the water line supplying the fire system.


1989-009

DATE OF OCCURRENCE: July, 1989

LOCATION: Edmonton, Alberta

SOURCE OF INFORMATION: Western Canada Water & Waste Association

SUMMARY: The failure of three wafer check valves on a fire system permitted the backflow of yellowish, oily water into the potable water system at a transit station.

DETAILS:

In July of 1989 a call from one of Edmonton's light rail transit stations indicated that a yellowish, oily water was observed in the public washrooms.

It was learned that a maintenance crew had used a fire hose to flush out a sewer line shortly before the incident occurred. The line to the fire hose was separated by a 4-inch ULC approved wafer check valve on the fire pipe stand and 2 8-inch ULC approved wafer check valves on the header of the sprinkler system. All three valves on inspection were found to have deposits which prevented the valves from closing tight.

The inspector recommended a R.P. be installed in the water line supplying the system as glycol was used in the stand pipe.


1989-010

DATE OF OCCURRENCE: August, 1989

LOCATION: Edmonton, Alberta

SOURCE OF INFORMATION: Western Canada Water & Waste Association

SUMMARY: Each time a fire pump was tested, the failure of a wafer check valve on a fire system permitted the backflow of brown water into a print shop.

DETAILS:

In August of 1989 a printing shop owner complained of brown water in the washrooms and in the equipment. The owner mentioned that the contamination appeared each time the tire warehouse next door tested their fire pump.

The inspector found that the newly installed fire system was separated from the potable water by a ULC wafer check valve. The owner was instructed to install a D.C.V.A. in the water line to the fire system. After the D.C.V.A. was installed, no further complaints were recorded.


1989-011

DATE OF OCCURRENCE: October, 1989

LOCATION: Edmonton, Alberta

SOURCE OF INFORMATION: Western Canada Water & Waste Association

SUMMARY: Investigation of a water quality complaint revealed that the water piping to a sink and drinking fountain was connected to the fire line hose cabinets.

DETAILS:

In October of 1989 the Edmonton Board of Health and the Cross Connection Control Office were called to investigate a complaint of contaminated water supplying a drinking fountain. The inspectors found that black iron pipe had been piped to supply fire hose cabinets as well as a drinking fountain and a sink.

The building where the drinking fountain and sink were located was used sparingly, causing a build up of contaminants. Plant officials were requested to re-pipe the domestic water and fixtures with potable water carrying material to a point upstream of the black iron pipe. A DCVA was also requested on the line supplying the fire hose cabinets.


1989-012

DATE OF OCCURRENCE: November, 1989

LOCATION: Federal Way, Washington

SOURCE OF INFORMATION: Federal Way Water & Sewer District

SUMMARY: The shut down of a water main for the installation of a fire hydrant resulted in the backflow of boiler water into the potable water system in a community pool building.

DETAILS:

On November 15, 1989 the Federal Way Water and Sewer District received a call from a community swimming pool that they had very little water pressure and hot water was coming out of the cold water tap.

An investigation indicated that a contractor installing a fire hydrant had shut down the main water without notifying the pool. The contractor thought the water service to the pool was off the water main on another street.

Not realizing their water was off, the pool did not shut down the boiler. The pressure in the boiler caused the boiler water to backflow into the potable water system and out of the cold water faucets when they were turned on.

The boiler had been recently cleaned and no chemicals had been added after cleaning.

The pool was informed that they were required to install a reduced pressure principle assembly on the boiler feed line.


1989-013

DATE OF OCCURRENCE: October, 1989

LOCATION: Edmonton, Alberta

SOURCE OF INFORMATION: "Edmonton Journal"/Watts Regulators

SUMMARY: A backflow incident contaminated the domestic hot water system in a research lab with a growth nutrient for micro-organisms.

DETAILS:

On October 25, 1989 the laboratory and offices of a research facility were shut down after a growth nutrient for micro-organisms backflowed into a hot water system.

A soupy, non-toxic fluid used as a growth nutrient was being injected into a fermenting vessel. Hot water, used for dilution, was provided by a direct cross-connection to the fermenting vessel. Because the injecting pressure was "too high", up to 150 liters of the growth nutrient backflowed into the domestic hot water system. The backflow incident was detected when staff noticed a smell coming from the hot water taps in the building.

Although the growth nutrient was not considered a health risk, contamination of the potable water supply could encourage the growth of any small amount of bacteria in the water supply.

The cold and hot water lines in the building were chlorinated and flushed.


1989-014

DATE OF OCCURRENCE: January, 1989

LOCATION: Edmonton, Alberta

SOURCE OF INFORMATION: Western Canada Water & Waste Association

SUMMARY: An open bypass valve on a holding tank pump for recycled water allowed "green" water to enter a plastic manufacturing plant's potable water.

DETAILS:

Workers at a plastic manufacturing plant were astonished to see green water flowing from the cafeteria water taps. They immediately notified the water department of the problem.

The investigator found that a bypass valve connected to the downstream side of a pump was inadvertently left open. This pump took recycled water from a holding tank to cool various equipment throughout the plant. Since the pump created a higher pressure than the City water supply it forced the water from the holding tank back into the potable water system. Fortunately, the green dye from the plastic manufacturing process alerted the employees of a problem before anyone drank the water.

Water lines were flushed and a reduced pressure principle backflow preventer, which was not bypassed, was installed in the line to the pump. Numerous other backflow preventers were also installed after a complete inspection of the facility was conducted.


1989-015

DATE OF OCCURRENCE: June, 1989

LOCATION: Maryville, Missouri

SOURCE OF INFORMATION: ABPA News, March/April 1993

SUMMARY: A vintage two story home, split into a duplex, was contaminated with "blue colored" tap water.

DETAILS:

On June 30, 1989 the owner of a vintage home that had been split into a one up, one down duplex, complained of "blue colored" water coming out of his taps during times of high water usage in the home. Investigation of the plumbing of the house revealed old galvanized water piping, judging by the investigator's experience, by this point in the pipe's age the pipe would be almost corroded closed. The following items were also found:

1. A flush valve in the water closet tank that fills below the water level of the tank without an anti-siphon device. This resulted in a cross connection of the potable water with the water in the water closet tank, which had a blue bowl cleaner added.

2. A boiler hot water heating system was found without any type of isolation on the cold water feed line.

3. A claw foot bath tub on the second floor with a sprayer hose attached to the below flood rim fill faucets.

Pressure taken at the exterior hose bib was 20 p.s.i.g., when the second floor sink, tub and lavatory faucets were opened, pressure at the hose bib dropped to 8 p.s.i.g. After opening these second floor faucets, a negative pressure was induced which backsiphoned the blue water from the water closet, resulting in "blue colored" water flowing from the spray hose on the tub faucet. The faucet was then opened on the first floor sink, pressure at the hose bib then dropped to 2 p.s.i.g. Opening the downstairs sink faucet induced a backsiphonage from the second floor tub faucet through the attached sprayer hose and an audible siphonage could be heard in the water closet.

The owner was advised of the necessary devices to eliminate the problems of backflow and backsiphonage.


1989-016

DATE OF OCCURRENCE: March, 1989

LOCATION: Fordyce, Arkansas

SOURCE OF INFORMATION: Arkansas Department of Health

SUMMARY: Propane gas backflows into city water supply causing three buildings to burn, fixtures to explode and several injuries.

DETAILS:

Household plumbing fixtures became incendiary bombs after propane gas from railroad tank cars was accidently placed in a city water system. Three persons were injured when explosions occurred after they flushed toilets in separate buildings. Two houses were destroyed and a local business seriously damaged by explosions and subsequent fires.

Investigation revealed an accidental crossover hookup [cross connection] caused the propane to enter the water system from a pressurized railroad tank car.

The crossover hookup occurred at a company about 500 yards from the sites of the explosions. The company cleans and refurbishes railroad cars and routinely works on cars carrying propane, methane and ammonia. When propane is present in a car, the company bleeds it off, pulls it through a tower and burns it off. Then steam, water and air is injected into the car to clean it.

A tank car at the rear of the plant site containing pressurized propane was located adjacent to a water line with a quick connect fitting. On his arrival at the company, the Fire Marshall discovered that a water hose with quick connect fittings on both ends was connected to the tank car and the water lines on the company site contained pressurized gas.


1989-017

DATE OF OCCURRENCE: June, 1989

LOCATION: Salt Lake City, Utah

SOURCE OF INFORMATION: Salt Lake City Public Utilities

SUMMARY: Backflow from a fire sprinkler system resulted in propylene glycol entering into a shopping mall's potable water supply.

DETAILS:

On June 29, 1989 the Salt Lake City Public Utilities received a complaint from a shopping mall that the water had a sweet smell and taste, and was foaming.

The complex has a combination fire and culinary water service. The antifreeze system is within 15 feet of the joint service, a check valve failed during several shutdowns of the fire system to replace sprinkler heads, while water was continuously being used by the beauty parlor and other tenants. There are seven such combination systems in this complex.

A double check valve assembly was installed ahead of the problem connection.


1990-001

DATE OF OCCURRENCE: Summer, 1990

LOCATION: Brentwood, Tennessee

SOURCE OF INFORMATION: Astra Industrial Services

SUMMARY: During the summer of 1990, approximately 1,100 guests of a racquet and country club became ill with an intestinal disorder in two mass incidents after consuming the club's contaminated water supplied from an auxiliary well.

DETAILS:

During the summer of 1990, approximately 1,100 guests of a racquet and country club became ill with an intestinal disorder in two mass incidents after consuming the club's contaminated water. The club obtained water from both the public water system and an unauthorized private well.

In 1984 the club informed the city that it had dug an additional well and connected it to the club's plumbing to permit the club to operate completely from the well. A month later the city requested that an approved backflow preventer be installed on the service line since the club violated state and local health laws prohibiting cross connections. The city lacked staff to follow up on the request and never inspected the facilities.

In August, 1990 it was discovered by state investigators that the club's well was unsealed and located 10 feet from a malfunctioning sewage pumping station. Club employees reported that a pool of fecal contaminated water between the well and the sewage pumping station appeared to be sucked into the ground whenever the well's pump was activated.

The city was alerted that the club was using an auxiliary water supply by the fact that water bills showed usage fluctuations between zero and 848,000 gallons a month between August 1989 and October 1990. The City of Brentwood was cited by the State for failing for two years to inspect and monitor any of the 69 locations the city considered as possible sources of contamination to its water supply (cross connections). The city stated that it lacked sufficient staff to inspect all the buildings. Instead, the city chose to focus on inspecting newly built structures.


1990-002

DATE OF OCCURRENCE: May, 1990

LOCATION: Rochester, New York

SOURCE OF INFORMATION: "The Democrat and Chronicle"/USC FCCCHR

SUMMARY: A hole in a single wall heat exchanger, combined with a bypass pipe around a backflow preventer, resulted in a chemical solvent contaminating a manufacturing building's water supply.

DETAILS:

On May 9, 1990 about 1,000 employees of a large manufacturing company went without potable water after chemicals were accidently mixed into the facility's water supply. No one reported drinking the contaminated water or suffering any ill health effects.

County health officials stated that the chemical was confined to one part of a building. The contaminant, a solvent which included aphtha, a coal derivative, as well as another chemical, had a strong odor. The solvent could cause nausea if swallowed.

The contamination occurred through a heat exchanger. When a hole opened in the inner solvent line, higher pressure in the solvent line forced the chemical into the water-filled line. A backflow preventer was in place on the water line to the heat exchanger. However, a bypass pipe was found installed around the backflow preventer, allowing the solvent to enter the building's water supply.


1990-003

DATE OF OCCURRENCE: January, 1990

LOCATION: Brighton, Colorado

SOURCE OF INFORMATION: "Rocky Mountain News" & Denver Post

courtesy of USC FCCCHR & City of Glendale

SUMMARY: During a routine check of the heating boiler in a middle school, a valve was left open allowing the boiler water containing the antifreeze ethylene glycol to backflow into the potable water system.

DETAILS:

On January 30, 1990 eight of the 450 students at a Brighton middle school were sent to the hospital for treatment for ethylene glycol poisoning. Blood tests revealed the students had no antifreeze in their bloodstream.

During a routine maintenance check of the heating boiler, a valve was left open allowing the boiler water containing the antifreeze ethylene glycol to backflow into the potable water system. No backflow prevention assembly was in place on the feed line to the boiler. The school principle stated that nobody spotted the lack of a backflow preventer on the boiler for six years the building has been in existence. Building officials stated they assumed the backflow preventer was installed during construction of the building.


1990-004

DATE OF OCCURRENCE: February, 1990

LOCATION: Seattle, Washington

SOURCE OF INFORMATION: Seattle Water Department

"Seattle Post Intelligencer"


SUMMARY: A valve separating the potable water system and an auxiliary water supply to an irrigation system was accidently opened by the fire department during a routine inspection, permitting water from a pond to be pumped into the potable water system at a golf course.

DETAILS:

On February 23, 1990 the Seattle Water Department received a complaint of discolored water from a customer in a neighboring water system that obtains its supply from the Seattle system. On February 23 and 24, 1990 positive total coliform and fecal coliform test results were received from water samples taken from a routine sample collection site near the point of supply to the neighboring system.

An investigation of water service and metering information revealed the existence of an auxiliary irrigation system supplying a golf and country club. Fluoride analysis of the water confirmed the existence of the auxiliary supply.

The golf course irrigation system was supplied from a pond on the property. A valve separating the potable water system from the irrigation system was opened by fire department personnel during a fire system inspection.

The cross connection was quickly detected because the regular sampling location for monitoring bacteriological quality was located at the club house kitchen. Bacteriological contamination of a water system through a cross connection is very difficult to trace.


1990-005

DATE OF OCCURRENCE: May, 1990

LOCATION: Tucson, Arizona

SOURCE OF INFORMATION: "The Arizona Daily Star"/Stone-Drew

SUMMARY: Drinking water at a police station was contaminated with water from the building's cooling system.

DETAILS:

The drinking water at the main police station in Tucson, Arizona was contaminated by water from the building's cooling system. The cross connection between the potable water system and cooling system was discovered by maintenance workers trying to determine why the closed cooling system was loosing water. The maintenance workers added red dye to the water in the cooling system that serves several downtown buildings. The dye later appeared in the water fountain and toilets in the police station.

Signs were posted in the police station warning people not to drink the water. City staff began the inspection of the plumbing in the 72,000 square-foot new building addition suspected of having the cross connection.

No information was given on what chemicals were in the cooling system or the actual type of cross connection found.


1990-006

DATE OF OCCURRENCE: November, 1990

LOCATION: Rensselaer, Indiana

SOURCE OF INFORMATION: "Indianapolis Star", Nov. 3, 1990

Stone-Drew (Febco)

SUMMARY: Six staff members of a middle school reported becoming ill after drinking water containing ethylene glycol that backflowed from the school's cooling system into the potable water system.

DETAILS:

On Thursday, November 2, 1990 the water supply in a middle school in Rensselaer, Indiana was contaminated by ethylene glycol antifreeze from the school's cooling system. The contamination was not detected until early Friday morning.

State Board of Health officials urged students and staff that may have come in contact with the water at the school to seek medical attention. Six of the 100 staff members were treated by a physician for such symptoms as light-headedness, headaches and blurred vision. None of the 650 students reported any ill effects.

The school flushed the domestic water system and installed a backflow preventer on the makeup line to the cooling system


1990-007

DATE OF OCCURRENCE: August, 1990

LOCATION: Vancouver, Washington

SOURCE OF INFORMATION: City of Vancouver, Washington

SUMMARY: Removal of a "one way valve" on a dental chair resulted in the backflow of air into a dental office water lines.

DETAILS:

On August, 1990 a complaint was received from a dental office of air in the water lines for more than a month. Discussions with the dentist and neighboring offices determined that the problem was isolated to the dental office.

The dentist had done some work on one of his dental chairs and removed a "one way valve", thus allowing air to enter the water line.

The dentist was required to install a reduced pressure principle assembly on the service line to his office.


1990-008

DATE OF OCCURRENCE: November, 1990

LOCATION: Central Kansas

SOURCE OF INFORMATION: "Kansas Rural Water Magazine"

Stone-Drew (Febco)

SUMMARY: A malfunctioning solenoid valve on an air compressor in a dental office resulted in the backflow of air into the public water system.

DETAILS:

Several residents in a community in central Kansas were experiencing air in the water. The employees of the water department traced the source to a dentist office.

An air compressor supplied 80 psi to the dental equipment. The water pressure from the city varied from 40 to 45 psi. A solenoid valve which isolates the sir supply from the water line malfunctioned. The air compressor was "over working" trying to keep 80 psi in the entire municipal water system.

The dentist was required to install a reduced pressure principle assembly on the water connection.


1990-009

DATE OF OCCURRENCE: June, 1990

LOCATION: Tucumcari, New Mexico

SOURCE OF INFORMATION: Drinking Water & Backflow Protection

January, 1991

SUMMARY: An unknown quantity of industrial chemicals is backpressured in the public water supply by a company that transforms wheat and barley into ethanol.

DETAILS:

On June 27, 1990 a farm owner in Tucumcari recalled leaving his lawn sprinkler on all night. Stepping outside he noticed the distinctive odor associated with the nearby ethanol plant. Checking his inside faucets he discovered the smell came from the water. Samples were taken but not analyzed for specific contaminants at that time. Later, the farmer's son-in-law drank some water and became sick to his stomach, the local doctor could do nothing to ease his discomfort. On the same day, the town mayor also became very sick after drinking a large amount of water, it took 48 hours for him to recover.

A local grain power company transforms wheat and barley into ethanol - also called grain alcohol. In the distilling process, it also creates several toxic by-products and an unmistakable, yeasty, brewery type odor. Between "batches" of ethanol, plant personnel use water to clean scale from the heat exchanger and distilling equipment.

A functional backflow preventer contained most of the plant's potable supply. But, an unprotected auxiliary line tapped the distribution main to supply emergency fire cannons. Plant personnel illegally tapped the auxiliary line at one fire cannon with a fire hose and connected it to the plant's flushing system. The hose remained connected and the valve left open when plant operations resumed. An unknown quantity of industrial chemicals were backpressured into the public water supply.

Water mains in the area were flushed for eight hours to clear them of contaminants. Water samples for analysis were taken four hours after the flushing began. Several heavy toxins were found in the water during laboratory analysis including: toluene, phenol, benzene ethanol, nonanoic acid, decanoic acid, octinol, octanoic acid, heptanoic acid, butanoic acid, silicon, diconic acid and four trihalomethanes.

Fortunately no one died, but this could have turned into a very tragic event.


1990-010

DATE OF OCCURRENCE: November, 1990

LOCATION: Sangamon County, Illinois

SOURCE OF INFORMATION: "Journal-Register" November 14, 1900

SUMMARY: Excess air pressure causes five toilets to explode in County Courthouse.

DETAILS:

In November, 1990 problems started at the Sangamon County Courthouse Building one morning when a water tank in the sub-basement filled with air. The air built up excessive pressure, forcing a blast of air into the restroom plumbing. The force was so great that five toilets were blown to pieces before the 2,000-gallon tank, which is usually filled equally with water and air, could be filled to its normal level.

Fortunately no one was hurt in the blast which witnesses said sounded like gunfire or a bomb. One woman, waiting to finalize her divorce, heard the explosion and thought her husband was blowing up the building.

This incident had happened in the same building twice before in the '60s and '70s, both times fixtures were blasted apart.

Workers flushed toilets in an effort to relieve the pressure, as they did so, the toilet in the judge's private restroom exploded.


1990-011

DATE OF OCCURRENCE: July, 1990

LOCATION: Salt Lake City, Utah

SOURCE OF INFORMATION: Salt Lake City Public Utilities

SUMMARY: Borate/Nitrite accidentally pumped into the potable water system at a retirement home

DETAILS:

On July 18, 1990 the Salt Lake City Public Utilities received a complaint of purple water coming from the taps at an elderly housing complex.

During the treatment of the water in the heating water system, the chemical Borate/Nitrite with Phenolphthalein indicator was accidentally pumped into the hot water (culinary) system instead of into the heating system.

The housing authority flushed the system three times. The analysis of the water taken after the flushing showed 0.1 mg/L of combined nitrate/nitrite in the sample. The system was flushed two or three times more until analysis of the water samples showed no nitrites present.


1991-001

DATE OF OCCURRENCE: June, 1991

LOCATION: Casa, Arkansas

SOURCE OF INFORMATION: "Rural Water"

"Arkansas Drinking Water Update"

SUMMARY: The failure of two single check valves in a series (unapproved backflow preventer) on the service line to a commercial chicken house permitted the backflow, into the public water system, of an antibiotic administered to chickens through the chicken house water system.

DETAILS:

In response to complaints from a customer on the Casa water system, it was determined that the water system was contaminated by backflow from a commercial chicken house. The chicken house had been receiving water from both the public water system and an auxiliary well connected to the chicken house plumbing. The water system connected to the chicken house included two single check valves in series for backflow prevention. The water in the chicken house was being used to administer an antibiotic solution to the chickens.

During the week of June 23, 1991 residents in the area served by the water main became concerned when the water became noticeably discolored. When made aware of the problem, the water system manager shut off the water service to the chicken house and flushed the water line extension servicing the area. The water meter serving the chicken house was later removed until proper backflow prevention could be assured.

The presence of the antibiotic in the water could have caused severe effects in humans who were hypersensitive to the drug. Due to these and other concerns, chicken and brooder houses are considered to be a high health hazard requiring the installation of a reduced pressure backflow prevention assembly. According to the Cooperative Extension Service, there are estimated to be at least 12,000 chicken houses in Arkansas, and it can be assumed that most, if not all of these houses administer a variety of necessary chemicals to their stock.


1991-002

DATE OF OCCURRENCE: June, 1991

LOCATION: Centralia, Washington

SOURCE OF INFORMATION: City of Centralia, Water & Wastewater

Utilities

SUMMARY: The backflow of water from an auxiliary well source resulted in a water main flushing program.

DETAILS:

On Wednesday, June 2, 1991 the City of Centralia Water Utility received several calls from residents complaining that their water was a yellowish color. Additional calls were received the following day. In response the water mains in the area of the complaints were flushed.

On Thursday, in response to more complaints, the water main flushing was continued. Bacteria and chlorine samples were collected; no chlorine residual was detected. The customer complaints noted that their water darkened on heating, clear water turned yellow to orange after standing, stained fixtures, and imparted an oily residue or slime on the water surface. Later lab results determined that the water was free of coliform bacteria but contained iron and manganese.

The utility notified the customers in the area of the complaints not to drink the water and then initiated a house-to-house survey to determine the cause of the contamination.

On Monday, June 8, a water utility crew found that a mill still had water flowing from a hose bib after the city water was turned off. The mill had a well as an auxiliary water supply. The well supply had just recently been interconnected with the supply from the City and was being used intermittently for vehicle washing. The water from the well was high in iron and manganese.

The direct cost to the City for the cross connection investigation, lab testing and water main flushing was approximately $6,000. Approximately 85 persons were affected. Several customers filed claims against the City.


1991-003

DATE OF OCCURRENCE: March, 1991

LOCATION: St. Petersburg, Florida

SOURCE OF INFORMATION: TREEO, University of Florida, and

"Gainesville Sun", March 30, 1991

SUMMARY: The mistaken connection of the water service for a new house to the reclaimed water distribution line resulted in the customer being supplied with treated wastewater for domestic consumption.

DETAILS:

A Saint Petersburg family that drank and bathed for a week in water that looked and smelled awful, finally figured out the awful truth; their water service to their new home was "hooked up backward". The family had been drinking treated wastewater meant for the lawn. The grass, on the other hand, had been thriving on the family's drinking water.

The family members stated that the water tasted awful and smelled bad.

State officials stated that the reclaimed water is treated to kill all viruses and most bacteria, and drinking it should not cause any serious health problems. The water had a high concentration of nitrogen, phosphorus and salts.


1991-004

DATE OF OCCURRENCE: April, 1991

LOCATION: Edmonton, Alberta

SOURCE OF INFORMATION: Western Canada Water & Waste Association

SUMMARY: A single 8-inch check valve on a fire system failed and allowed contamination of the potable water supply to the restrooms in a transit station.

DETAILS:

In April of 1991 an LRT station experienced problems with the water in the staff washrooms and in the janitor's room. Inspection of the facility found that the fire system header was separated from the domestic water system by a single check valve. Examination of the check valve found that rust build up kept it 3/4 inch ajar.

Water samples taken to an independent laboratory had the following results: Fe (mg/L) 0.99, Pb (mg/L) 0.39, P (mg/L) 697.9.

Water samples taken from the buildings on either side of the station were normal.

a DCVA was recommended to be installed in the water line supplying the fire system.


1991-005

DATE OF OCCURRENCE: September, 1991

LOCATION: Uintah Highlands, Utah

SOURCE OF INFORMATION: "Deseret News"/Oregon Health Division

SUMMARY: About 100 homes were contaminated after a weed killer was backsiphoned into the public water system.

DETAILS:

Residents in the northern Utah community of Uintah Highlands were told not to drink the water after a weed killer, TriMec, was accidentally sucked into the water lines. The system was contaminated when a grounds keeper at a cemetery apparently allowed the chemical to be siphoned into the water system.

About 100 homes were believed affected, although some of the chemical may have entered the rest of the system that serves about 2,000 homes.

Residents were asked to open water taps for at least 20 minutes. If they notice peculiar smells or color, they were requested to leave the water running. Residents were urged to seek alternative water sources, such as bottled water.


1991-006

DATE OF OCCURRENCE: December, 1991

LOCATION: Vancouver, Washington

SOURCE OF INFORMATION: City of Vancouver Water Department

SUMMARY: A boiler cleaning compound was accidently pumped into a school's water supply instead of the properly protected boiler system.

DETAILS:

On December 2, 1991 a boiler technician pumped about 2 gallons of a cleaning compound into what he mistakenly thought was the boiler feed line in a school. The line was part of the domestic water system in the school.

The principle of the school discovered the cross connection when one of the teachers said that the water tasted soapy. The principle, knowing the boiler was being cleaned, immediately notified the technician. The water system in the school was flushed overnight.

The boiler was isolated by a reduced pressure principle assembly. However, the chemical was injected up stream of the assembly. To prevent a future occurrence, all the piping in the boiler room was marked to show their contents.


1991-007

DATE OF OCCURRENCE: June, 1991

LOCATION: Edmonton, Alberta

SOURCE OF INFORMATION: Western Canada Water & Waste Association/

City of Edmonton, Alberta

SUMMARY: The failure to properly flush highly chlorinated water from a new 8-inch pipe before placing it into service resulted in the water system of a building being polluted.

DETAILS:

In June, 1991 a water quality complaint was received from a local college. When the water quality inspector arrived, he noticed a strong chlorine odor coming from the lawn where a hose had been left running. Two of the water department's troublemen had already isolated the area and had taken samples from fire hydrants on the main water distribution system. These samples were within normal parameters, indicating that it was an internal problem. Water samples taken inside the complex showed chlorine levels higher that what the test equipment could measure.

Upon investigation it was found that the mechanical contractor had installed a new eight inch water line to supply the existing building as well as a new addition. The old service was to be abandoned. The new line was super chlorinated to disinfect it; then drained using a garden hose connected to a cap at the end of the line. According to the contractor's foreman, water samples were taken to a lab for testing. Apparently, the samples were approved. However, it was not substantiated that these samples were ever taken. Thereafter, a fire hose was connected from the new system to the existing water line. The old system was then turned off at the water meter and the new system turned on. The chlorine in the new water line had not been properly flushed, resulting in a tremendously high concentration of chlorine.

The contractor and staff were instructed to flush every faucet and outlet in the building. By 6:00 a.m. the next morning, a sample taken to the water treatment lab showed chlorine concentrations were down to normal, 0.04 mg/L. Twenty seven other chlorimeter tests on the hot and cold water system, throughout the complex revealed that the chlorine levels were within acceptable ranges.


1991-008

DATE OF OCCURRENCE: April, 1991

LOCATION: San Antonio, Texas

SOURCE OF INFORMATION: San Antonio Express News, April 20, 1991

SUMMARY: Faulty check valves on a water chiller allowed bacterial contamination of an Air Force Base water supply.

DETAILS:

Routine water samples taken at an Air Force Base in early April, 1991 and then tested by San Antonio Metropolitan Health District showed the presence of infectious bacteria.

The 22,000 workers and residents were ordered to boil drinking water or get water from substitute supplies until the source of the contamination was found and cleared up.

Investigators pinpointed the source of contamination as two check valves that had frozen open on a water chiller. The water in the chiller is exposed to open air and is susceptible to contamination from a variety of sources, including bird or squirrel droppings. Symptoms of coliform bacteria include diarrhea, cramps, nausea, headaches and fatigue. However, little increase was noted in the number of gastrointestinal problems at the base clinic.

The faulty check valves were replaced, and the base water was chlorinated more than usual. Water pipes in the two most severely areas of the base were flushed.


1991-009

DATE OF OCCURRENCE: May, 1991

LOCATION: Selden, New York

SOURCE OF INFORMATION: Drinking Water and Backflow Protection

May, 1994 - Volume 11, Number 5

SUMMARY: A cross connection between the air conditioning unit and domestic water line at a college results in ethylene glycol in the potable water supply.

DETAILS:

On May 1, 1991 complaints of water quality at a community college in Selden, New York was reported to The Suffolk County Department of Health Services. The water was reported to taste and smell "unusual". All the complaints originated from the school library.

Analysis of water samples taken at the library building confirmed the presence of ethylene glycol concentrations of up to one percent by volume.

The large commercial air conditioning system utilizes cooling towers installed on the exterior of the building. Seasonal freeze protection is required. Each fall, the library air conditioner is taken off-line by replacing the water with approximately 55 gallons of ethylene glycol. In the spring, the antifreeze was purged from the system and replaced with water. The water line to the system was controlled by standard gate valve and a pressure regulating valve. The gate valve was opened seasonally providing water and dispensing ethylene glycol to waste.

There are two possible reasons why the backflow incident occurred. The first suggests the water pressure in the building was less than the air conditioner during expansion and contraction in the coils located in the cooling tower. The gate valve and pressure regulator failed to prevent backflow resulting in a dilute solution of ethylene glycol entering the domestic water supply.

The second explanation might be attributed to the fact the local water purveyor had drained the water tower in the vicinity of the library for maintenance. The reduction of building water pressure was a likely result.

All water fixtures on the campus were posted with warning signs, and the fixtures were flushed for two days. The main domestic water supply to the campus was fitted with an acceptable backflow prevention assembly.

1991-010

DATE OF OCCURRENCE: June,1991

LOCATION: Missouri

SOURCE OF INFORMATION: ABPA, November/December 1992

SUMMARY: Trichloroethane enters a municipal water supply due to a cross connection at the newspaper office. Disorganized flushing by utility personnel scattered the contaminant throughout the distribution system.

DETAILS:

On June 18, 1991 the manager of a newspaper office in a "not so small" town in Missouri called the Department of Natural Resources to complain of a strong solvent odor in the drinking water. Investigation determined the strong solvent odors were in the municipal water system as the odors were present in fire hydrants at least one block south and one block west of the newspaper. Samples were collected from the newspaper office and several locations surrounding that office. During the sampling it was determined that city staff had flushed water mains in the area to try to remove the contaminant.

Results of samples collected revealed the presence of 1-1-1 trichloroethane. Because of the unstructured way the flushing was done by the city, samples were collected again on June 24 at locations chosen to define the area of contamination. Analysis indicated that trichloroethane was present in all samples. The levels were higher than those samples collected June 18, with the highest level being 420 micrograms per liter, high enough to be alarming, but the locations of the samples with the highest levels did not make sense. Investigation revealed that city staff had again flushed the water mains on June 21, in an effort to control the solvent odors.

At this point it was difficult to tell whether the trichloroethane was entering the water mains as a result of cross connection or a spill. Three businesses in the area used trichloroethane, the newspaper office, a machine shop, and an automotive garage. The machine shop and garage were ruled out as the cause.

A trichloroethane/water solution is pumped onto a portion of the press at the newspaper office. The water fill line was submerged in the solution tank. A regular check valve was in the water line to the solution tank. It is believed that high levels of trichloroethane entered the municipal distribution system due to a cross connection at the newspaper office. Disorganized flushing scattered the contaminant throughout the system and hampered the ability to identify and address the problem.


1991-011

DATE OF OCCURRENCE: October, 1991

LOCATION: Southgate, Michigan

SOURCE OF INFORMATION: Drinking Water & Backflow Prevention,

June, 1992

SUMMARY: Parasitical worms were sucked into the drinking water after a water main break.

DETAILS:

Parasitical worms were found in the water at two homes in Southgate, Michigan on October 1, 1991 after the backflow prevention system on a privately owned underground sprinkler system malfunctioned coupled with a water main break.

The Wayne County Health Department determined that an atmospheric vacuum breaker had malfunctioned and was stuck in the closed position, there was a water main break that caused a vacuum in the system. When the water pressure dropped the vacuum in the system sucked some water from the sprinkler into the city water, but was only distributed to two homes.

One homeowner found the worms swimming around in his bathtub when he started filling the tub for his child. He was appalled to find the critters, as well as rust and other debris in his water. He was still finding living things in his water the following day.

The contractor who installed the sprinkler system did not have a city permit and used a "cheap" atmospheric vacuum breaker. When it malfunctioned at the same time as the water main break, the nematodes were siphoned into the system.

The resident who owns the sprinkler was cited by the county for improper installation.


1992-001

DATE OF OCCURRENCE: February, 1992

LOCATION: Atlanta, Georgia

SOURCE OF INFORMATION: ABPA News, September/October 1993

SUMMARY: Cleaning chemicals, used to remove grease from a commercial kitchen hood, is backsiphoned into the potable water system.

DETAILS:

On February 6, 1992 there was a report that water from the men's grill bar sink, situated in a golf club, was burning people's hands as if it contained acid.

The building superintendent investigated and observed brownish tainted water at the downstairs bar sink, he cautioned everyone not to use the water and then checked the upstairs plumbing. He found tainted water in the rest of the building.

The Atlanta Plumbing Department and the Water Bureau were called to investigate. Water samples taken from several points in the building revealed a pH level of 10.0, this represented an extremely high alkalinity or caustic level in the water.

Earlier, a hood cleaning company had completed a cleaning operation on the club's kitchen hood. The cleaning solution was delivered by a high pressure spray nozzle to remove grease accumulation.

The cleaning chemicals were placed in a tank and mixed with water supplied by a garden hose from a club house hose bib. The tank with the solution was then pressurized by a air compressor to 90-100 psi, while maintaining a continuous "water supply" to the tank. The water system pressure, however, was only 50-55 psi. Thus part of the solution was forced out of the spray nozzle, and part into the potable water system.

The hood cleaning company stated that no acid was used in the cleaning mixture and provided the formula - xanthum gum, sodium hydroxide and isopropyl alcohol. The cleaning equipment did not have a backflow prevention device, nor did the club's hose bib supplying water to the equipment.

The golf club was required to install backflow prevention devices.


1992-002

DATE OF OCCURRENCE: 1992

LOCATION: Edmonton, Alberta

SOURCE OF INFORMATION: Western Canada Water & Wastewater Assoc.

SUMMARY: Employees of a plastic manufacturing company disconnect a vacuum breaker causing backpressure of potassium hydroxide and calsolene oil into the city system.

DETAILS:

Edmonton's water department received a call from a plastics manufacturing plant complaining of sudsy water in their hot and cold water lines. Investigation of the facility found that all the equipment, and individual outlets had the appropriate backflow prevention devices except one hose bib. A hose was connected to this outlet and attached to the process water pump so that it could be primed. Apparently, a hose connection vacuum breaker had been installed when the building was under construction. However, the operators found it a nuisance, as every time the pump was turned the hose connection vacuum breaker started to spray water from the relief ports. It seemed reasonable to simply take the hose connection vacuum breaker off and connect the priming hose directly to the hose bib. This certainly solved the spillage problem but it also created an unseen hazard. The pressure the pump produced overcame the city water pressure and forced the process water, which contained potassium hydroxide and calsolene oil, back into the domestic cold water supply.

Employees at the site had been drinking water the day of the contamination. They complained of raw throats. Fortunately, not enough of the substance had been consumed to cause any serious health effects.

A reduced pressure principle backflow preventer, to the process area, was installed along with a proper backflow preventer to the process water line used to prime the pump.


1992-003

DATE OF OCCURRENCE: April, 1992

LOCATION: Winnipeg, Manitoba

SOURCE OF INFORMATION: Western Canada Water & Wastewater Assoc.

SUMMARY: A Seniors Residence experiences intermittent "blue colored" water in taps.

DETAILS:

It began in April, 1992 when a tenant of a Seniors Residence complained of periodic "blue colored" water coming from her taps. Laboratory Services collected cold water samples but no blue coloration was evident and test results were inconclusive.

In July, 1992 the tenant returned from abroad and complains of "blue" water again. Tenant advises that the blue water condition is intermittent and usually occurs in the bathroom but has occurred in the kitchen sink. According to the Chief Maintenance person, this is the only tenant in the complex that has experienced the blue water problem.

The Backflow Prevention Branch of City Health conducted an investigation and inspection to determine the cause of the blue water. Plumbing system and heating/cooling system were checked. Suites along the vertical riser plumbing system were checked for possible backflow/cross connection situations, as well as the main floor businesses (hair dresser, bakery/restaurant). Water samples were collected from various locations for analysis. Tenants in three suites above the vertical riser were found to be using blue toilet bowl disinfectant cleaners in their toilet tanks. Because of the plumbing deficiencies, blue disinfectant water could possible backflow into the water system under the right conditions. Plumbing deficiencies were corrected immediately.


1992-004

DATE OF OCCURRENCE: October, 1992

LOCATION: Ritzville, Washington

SOURCE OF INFORMATION: Backflow Management Inc.

SUMMARY: Backsiphonage resulting from a venturi effect caused recurring algae problem in public water distribution system.

DETAILS:

For some time, the Ritzville public water distribution system had a recurring problem with cyanobacteria, or blue-green algae, a type of algae dependant on light for photosynthesis. A study of the entire distribution system was undertaken to determine any possible source of surface water contamination. No creeks, ponds or other bodies of water were noted.

The source of the algae was eventually traced to a new reservoir. A 16-inch pipe served as both inlet and outlet. The drain from the reservoir was a 12-inch line that branched from the 16-inch line. The drain line discharged into a partly submerged sump located approximately four feet in elevation below the reservoir.

Algae growth was noted in the drain sump. As the sump was being observed, it was also noted that water was flowing from the sump into the drain pipe. The drain line valve could not be closed tight. When water was pumped into the reservoir, the venturi action past the drain connection syphoned water from the sump. When the pumps stopped, the siphonage was observed to stop, confirming the venturi effect.


1992-005

DATE OF OCCURRENCE: August, 1992

LOCATION: Kennewick, Washington

SOURCE OF INFORMATION: City of Kennewick

SUMMARY: A complaint of dirty water at a restaurant reveals CO2 backflowed into city water system.

DETAILS:

On August 14, 1992 a cross-connection specialist responded to a complaint by the owner/manager of a restaurant of dirty water. Upon arrival it was found the meter was running backwards, the meter was turned off and the service line ordered to be flushed.

When the water was turned on to flush the service line, the work crew noticed an unusual "blast of air" followed by very black water.

Investigation revealed the problem was first noticed when the drive-through window beverage dispenser quit working and dirty water was noticed in a nearby sink.

A smell that was recognized as CO2 gas was coming out of the faucets at the back of the restaurant. Checking the CO2 tanks, the on line tank contained 500-525 psi. The manager had connected the tank just prior to the dirty water problem. At that time it was a new, full tank with 800 psi.

Now knowing that CO2 had backflowed into the water main over coming the city water pressure of 65-70 psi in the 10-inch steel main, the water main was isolated and systematically flushed to remove any contamination.

All three carbonators were checked to determine which had malfunctioned.

The two front counter dispensers had small metal filings in the dual check valve 0-rings.

The drive-through window dispenser was found to have three small pieces of rust and a spring stuck in the open position. This caused the carbonator to burn out.

After three hours of flushing, laboratory analysis reported the water to be free of any bacteria.

The restaurant was closed until a backflow preventer could be installed on the water supply to the carbonators.


1993-001

DATE OF OCCURRENCE: September, 1993

LOCATION: Boston, Massachusetts

SOURCE OF INFORMATION: ABPA News, September/October 1994

SUMMARY: A restaurant's malfunctioning soda system caused suction within the piping system forcing a chemical agent into the potable water system.

DETAILS:

On September 2, 1993, the Cross Connection Control Office in Boston, Massachusetts received a call from the owner of a restaurant, that "blue" water was coming out of the kitchen sink and was also present in the soda dispensing system. There was also an odor and bad taste to the water.

Inspectors found that the dishwashing system had a direct cross connection present. The blue chemical drying agent was connected to the dishwasher supply line without backflow protection. The owner was asked to remove the chemical supply line from the five gallon drum of chemical drying agent, also to thoroughly flush the water lines and install an approved RPBA device before reconnecting the drying agent to the dishwashing system.

The following day, a licensed plumber, while installing the RPBA device, found the actual cause of the cross connection. The soda system's pump was continuously engaging and creating suction within the internal piping system. During the night, when there was no water usage, the continuous engaging of the pump caused a suction within the restaurant piping system. The chemical agent was sucked back into the dishwasher supply line and from there throughout the restaurant.


1993-002

DATE OF OCCURRENCE: November, 1993

LOCATION: Melville, New York

SOURCE OF INFORMATION: Drinking Water and Backflow Prevention

May, 1994 - Volume 11, Number 5

SUMMARY: A cross connection resulted when a washing machine hose was connected to a hose bib located on both an air conditioner and a potable water system at a blood bank.

DETAILS.

On November 16, 1993 the drinking water section of Suffolk County Department of Health Services was made aware of a serious cross connection hazard associated with the operation of a large commercial air conditioning system using exterior mounted cooling towers at a large full service blood bank. The air conditioning system capacity is approximately 80-90 gallons of ethylene glycol. The mechanical room is located above the laboratory and it contains condenser/pumps for this system.

The domestic water piping was installed through the mechanical room, close to the condenser/pumps. The cross connection was constructed using a standard washing machine flex hose connected to a boiler drain type hose bib located on both the air conditioner distribution loop and the potable water supply. To purge air from the condensers, maintenance men constructed a bridge between the air conditioning loop and potable water system and then pressurized the system, air was then vented to the atmosphere using a second hose bib on the discharge side of the condenser.

Staff at the blood bank received complaints about soapy and sudsy water and the water was colored. The first incident was noted when the main ice-making machine, located in the laboratory area, would not produce ice. Maintenance men then recalled the washing machine hose connection, and upon investigation, found the cross connection still in place, the connection had remained undisturbed, with all valves in an open position, for an estimated nine or ten days.

The volume of ethylene glycol that contaminated the domestic water supply remains unknown, although conditions were high enough to inhibit ice production. The fact that no injury resulted from this contamination incident is remarkable considering the amount of fluids blood donors are required to consume following donation.

As a result of this incident, a reduced pressure assembly was installed internally on the domestic water line servicing the air conditioning system and the boiler drain/hose bib was removed.


1993-003

DATE OF OCCURRENCE: November, 1993

LOCATION: Wilson, North Carolina

SOURCE OF INFORMATION: Drinking Water & Backflow Prevention

February, 1994 - Volume 11, Number 2

SUMMARY: Chemicals from an x-ray developer were backflowed into the potable water supply of a medical facility.

DETAILS:

On November 17, 1993 the City of Wilson, NC Water Distribution Division received a complaint from a medical facility of a strange, bitter taste and strong chemical odor to their water.

Upon investigation, a cross connection was discovered with a chemical mixer used in x-ray development. The equipment combined water with three part developer and two part fixer. Water was added to the mixer through an indirect cross connection with a garden hose and hose bib. The hose bib was not protected with a hose bib vacuum breaker as required by code, although the device was in installed when the plumbing and final certificate of occupancy were issued for the building.

On the evening of November 15, water distribution personnel working with a private utility contractor cut a section from the eight-inch water main in front of this facility to replace a leaking tapping sleeve with a Tee. The tapping sleeve served a new street where the clinic's service was located. The work was done under during evening hours, because it was understood that the clinic would lose water service temporarily. When this work was done, it apparently created a backsiphonage on the clinic's water system.

Analysis of water samples taken from the clinic showed no chlorine residual and a pH of nearly 8.0. These results are consistent with the presence of sulfate and sulfite, chemicals found in developer and fixer.


1993-004

DATE OF OCCURRENCE: January, 1993

LOCATION: Vancouver, British Columbia

SOURCE OF INFORMATION: Vancouver Health Department

SUMMARY: Blue toilet sanitizer water is backsiphoned into potable water system.

DETAILS:

In January, 1993 the Vancouver Health Department received a complaint from a customer that his hot water was coming out blue and soapy. On investigation, it was noted that light blue water flowed from the hot water side, while the cold water appeared clear.

On questioning the complainant and reviewing the building water system, it was determined that the rear outside tap had frozen and sprung a leak during a recent cold spell. The owner had shut off the main water supply valve and had cut and capped the water line leading to the outside tap. It was during this event that the complainant noted blue water for the first time.

On further investigation it was noted that the toilet in the attic bedroom had blue toilet sanitizer in the tank and bowl. The attic washroom had not been used for a long period of time and the owner had forgotten about the sanitizer.

It was concluded that some of the toilet tank water containing colored sanitizer was drawn into the building's water distribution system during the water line break and repair event. A considerable amount of cold water had been run after the event, which flushed the cold water side clear prior to inspection.


1993-005

DATE OF OCCURRENCE: May, 1993

LOCATION: Southern Oregon

SOURCE OF INFORMATION: Conbraco Industries Inc.

SUMMARY: Non FDA approved plastic hose causes bad taste and odor in beverages from a pop machine.

DETAILS:

A plumbing contractor installed a stainless steel backflow assembly in a soda pop machine at a deli, the device was tested and there was no problem.

A few hours later, the deli owner called the plumber and complained of a bad taste and odor in the water. The installation of the device was double checked and it was confirmed there was no brass installed down stream of the device. The CO2 service machine was at least 5' away from the device.

Further investigation found the problem to be a bad, non FDA approved, flexible plastic hose. This was replaced with a FDA approved brand. There were no further complaints.


1993-006

DATE OF OCCURRENCE: July, 1993

LOCATION: Coos Bay, Oregon

SOURCE OF INFORMATION: Backflow Management Inc.

SUMMARY: Water from a drainage pond, used for lawn irrigation, is pumped into potable water supply of a housing development.

DETAILS:

On a site formerly used by a sewer cleaning company to dispose of septic tank "pumpings", a housing development was allowed to be developed after the site had been covered and compacted. The occupants of one home installed a pump for irrigation in the ponded drainage flowing from this fill area. Eventually the pump failed. The wife, noticing the need to irrigate the lawn but aware the pump was in for repair, connected a hose from the house to the sprinkler system. The husband returned with the repaired pump, installed it, and turned it on pumping the highly contaminated drainage water through the hose, and into the water main in the street and into the elevated storage tank serving their area.

Fortunately, a meter reader for the water utility was at the site and notified his office and the utility was able isolate the contaminated area to the 7 or 8 homes in the housing development and to the elevated storage tank that served the development.


1994-001

DATE OF OCCURRENCE: September, 1994

LOCATION: Monterey, California

SOURCE OF INFORMATION: "Monterey County Herald", October 7, 1994

SUMMARY: A defective backflow device in the water system of the County Courthouse apparently caused sodium nitrate contamination that sent 19 people to the hospital.

DETAILS:

A defective backflow device in the water system of the County Courthouse apparently caused contamination of sodium nitrate that had been used in the building's boiler and cooler.

On September 29, 1994, nineteen people became sick enough to require medical attention, all had drunk coffee from the courthouse snack bar. Samples taken from the coffee urn contained high concentrations of sodium nitrate.

Employees of the courthouse had noticed "brown, rusty" water in the toilets, sinks and drinking fountains that morning, they let the water flow until it cleared up. However, the proprietor of the snack bar is legally blind and did not notice the brown water in his sink, and water flowing through the coffee machine comes directly from the courthouse water system. "Naturally it comes out brown from the coffee urn".

The backflow valves that may have malfunctioned were changed or repaired.


1994-002

DATE OF OCCURRENCE: July, 1994

LOCATION: Syracuse, New York

SOURCE OF INFORMATION: Drinking Water & Backflow Protection

March, 1995 - Volume 12, Number 3

SUMMARY: An 8-inch reduced pressure principle in the basement of a hospital discharged under backpressure conditions dumping 100,000 gallons of water into the basement.

DETAILS:

A veterans hospital in Syracuse, New York was closed for several days in July, 1994 following when it appeared that an 8-inch reduced pressure principle assembly located in the basement discharged under backpressure conditions. More than 100,000 gallons of water dumped into the basement filling it to a depth of 8 feet. Submerged pumps, exchangers, and boilers failed. Domestic water supplies were contaminated with fouled discharge.

The relief valve did not fail. A reduced pressure principle assembly is designed to prevent backflow under back pressure conditions. If check valve no, 2 fails, then potentially contaminated backflow is discharged from the plumbing system to prevent possible contamination of the potable supply.

The floor drains did not work properly because the capacity was not large enough. Possible flow restrictions of dirt, hair, cigarette butts, and other waste material did not help the matter.

The cost of clean up, patient transfer may hit $2,000,000. This may be a conservative estimate considering today's litigious society.


1994-003

DATE OF OCCURRENCE: May, 1994

LOCATION: Franklin, Nebraska

SOURCE OF INFORMATION: Drinking Water and Backflow Protection

September 1994, Volume 11, Number 9

SUMMARY: While working on a chiller unit of an air conditioning system at a nursing home, a hole in the coil apparently allowed Freon to enter the circulating water and from there into the city water system.

DETAILS:

A backflow of Freon into the drinking water supply of Franklin, Nebraska left residents without water for 6 days.

Workers accidently released the chemical refrigerant into the city water system while repairing a nursing home air conditioning unit. A hole in the coil of the unit apparently allowed Freon to enter the water that was circulating through the air conditioner, a city domestic water line was connected to the chiller, which is common for commercial air conditioning systems. The Freon, which was being pumped in with about 1,000 pounds of pressure, backed up into the city water main, contaminating the water.

City officials became aware of the problem when the city residents (pop. 1,100) began complaining of bad tasting water that caused a burning sensation in the mouth. No one became sick from drinking the water.

Residents were without water for six days while the drinking water system for the town was flushed three times before tests results showed the system to be free of Freon.


1994-004

DATE OF OCCURRENCE: June, 1994

LOCATION: Carmichael, California

SOURCE OF INFORMATION: Drinking Water & Backflow Prevention

September 1994, Volume 11, Number 9

SUMMARY: The blue tinted water in a pond at an amusement park backflowed into the city water system and causes colored water to flow from homeowners faucets.

DETAILS:

Water that had been dyed blue for dramatic effect in an amusement park's bumper-boat ride pond in Carmichael, California, flowed back through an inlet and into the main domestic water pipe that feeds neighboring houses and businesses. The water flowed from the faucets the color of Windex, and ice machines churned out blue ice cubes.

The three foot deep pond has a pump that shoots up water as amusement park boaters bump into each other in the 111,000 square foot lake. The water pressure in Carmichael is fairly low and the pump pressure was greater than the general water pressure so it did not take much to pump blue-dyed water into the system without a backflow preventer.

The blue dye was labeled non-toxic and the escaped pond water was cleansed of harmful bacteria as it mixed with the municipal water supply. Samples of the dye and pond water were sent for laboratory testing to be absolutely certain it was safe to drink.

The city water system was flushed until the water ran clear. The amusement park ride was ordered shut down until an approved backflow prevention device was installed.


1994-005

DATE OF OCCURRENCE: October, 1994

LOCATION: Los Angeles, California

SOURCE OF INFORMATION: California-American Water Company

SUMMARY: A film company shooting a commercial for television accidentally introduced a chemical into the potable water system.

DETAILS:

A film company was using a ranch in the northeast section of California-American's water system for their filming location. In the scene they were shooting, it was snowing. The film crew was spraying artificial snow from a pressurized tank for special effects. The artificial snow was generated from a 55 gallon tank of Macrojet I Concentrate. The water truck that furnished water for this process failed to work properly. As a result, a special effect's person connected a garden hose to the house hose bib. The pressure in the tank forced the chemical into the potable water line when the hose bib was opened. Approximately 30 gallons of the solution was back-pressured into the potable water system.

Consumers on the affected cul-de-sac street began calling the water company complaining of brown soapy water coming from their faucets. Water company employees instructed them to flush both hot and cold faucets until they ran clear. The water company began flushing the system from a 2" blow-off valve at the end of the 8" main for several hours until the water ran clear. Bottled water was supplied to the homes in the area. Flushing was continued for several more hours the next day until the water was safe to drink.

Because this location has been used many times before for filming, and to avert this problem from recurring, a reduced pressure principle backflow prevention assembly was required to be installed on the consumers service line.


1994-006

DATE OF OCCURRENCE: April, 1994

LOCATION: Des Moines, Iowa

SOURCE OF INFORMATION: Department of Public Health, Iowa

SUMMARY: A backflow of water from the Capitol Building chilled water system contaminates potable water with Freon.

DETAILS:

On April 20, 1994 the Iowa Department of Public Health received a complaint of discolored bad tasting water at the Capitol, a sample had been taken and an undetermined amount of Freon was present.

The available information points to a backflow of water from the Capitol chilled water system to the potable water piping in the area of the Senate lounge. This apparently occurred in the afternoon or evening of April 18. A combination of circumstances contributed to the backflow.

1. The chilled water system was being filled from the potable water system on April 18.

2. The booster pump used to get added volume to the chilled water system was being replaced through the day. The chilled system was being filled with city main pressure water.

3. Perhaps because of #2 above, the by-pass gate valve in the supply line to the chilled water system was left open for at least four hours on April 18.

4. The booster pump was operated briefly April 18, evening, then shut down because a leak was found just downstream of the pump.

5. The area where discolored, bad tasting water was found is immediately downstream of the line serving the chilled water system.

The backflow occurred because of an unprotected cross connection between the chilled water system and the potable water system. This cross connection has been provided with adequate protection. The building was also provided with a containment backflow prevention assembly.


1994-007

DATE OF OCCURRENCE: June, 1994

LOCATION: Indiana

SOURCE OF INFORMATION: "Journal and Courier" Newspaper

SUMMARY: Water main break caused a drop in water pressure allowing anti-freeze from an air conditioning unit to backsiphone into the potable water supply.

DETAILS:

Complaints about discolored and bad-tasting water in an Indiana university building alerted officials to a mechanical malfunction that allowed anti-freeze to leak into the water supply.

Workers are almost certain the ethylene glycol first got into the building's drinking water supply sometime after a water main break caused a drop in pressure which allowed anti-freeze from an air-conditioning unit outside the building to be siphoned back into the water supply. Officials aren't sure how much of the anti-freeze leaked.

The water supply is connected to the air conditioning unit to maintain an adequate mixture of water and anti-freeze. A mechanical check valve apparently failed.

The drinking water supply was shut off for one full day while plumbers flushed the building's pipes. Employees were still asked not to drink the water. Full service of drinking water resumed the following week after tests showed no trace of contaminant.

All workers who drank the contaminated water were examined by a doctor, no serious illness was reported.


1994-008

DATE OF OCCURRENCE: August, 1994

LOCATION: Seattle, Washington

SOURCE OF INFORMATION: Seattle Water Department

SUMMARY: An Ethylene Glycol cooling system was illegally connected to the domestic water supply at a veterinary hospital.

DETAILS:

Ethylene Glycol was discovered in the domestic water supply at a Seattle veterinarian hospital. While looking for a water leak in the cooling system it was discovered water from a domestic hose faucet was directly connected to the non-potable cooling system.

The building was completely flushed three days in a row. Hose faucets were removed from the return and supply lines on the cooling system to eliminate the possibility of domestic water being connected to the hose faucets.


1994-009

DATE OF OCCURRENCE: May, 1994

LOCATION: Columbus, Ohio

SOURCE OF INFORMATION: "Contractor" Magazine, December 1995, courtesy of USC FCCCHR

SUMMARY: An ice machine connected to a sewer sickened dozens of people attending a convention.

DETAILS:

In May 1994, more than 1,000 people attended a convention in Columbus, Ohio. About two weeks after the convention was over, a small number of call started coming into the health department. All of the callers assumed that they had contacted food poisoning at restaurants at the convention. Giardia was ultimately blamed for the illnesses. It has an incubation period of five days to two weeks. Its symptoms can be subtle, depending upon one's resistance. Symptoms included diarrhea, intestinal cramps, and nausea.

The health department inspected the restaurants and did not find any problems. As more calls were received, it was realized that the callers had all been at the same convention. The health department interviewed the people attending the convention. The health department mailed 1,200 surveys to those attending the convention will an itemized list of every food served. When the surveys were returned, a statistical analysis showed no correlation.

The first survey did not include beverages. A second survey on beverages showed that people who had drinks with ice at one particular cocktail party were likely to become sick.

An inspection found an ice machine. The unit had a demineralizing filter with a drain hose directly connected into a floor drain.


1995-001

DATE OF OCCURRENCE: March, 1995

LOCATION: New Roads, Louisiana

SOURCE OF INFORMATION: Department of Health, Louisiana

SUMMARY: The herbicide Paraquat and Atrazine was backsiphoned into the city water system after a water line is cut.

DETAILS:

A work crew accidentally cut the water line on March 21, 1995 while a farmer, some distance away, was diluting several gallons of Paraquat Dichloride and Atrazine in a 300-gallon spray tank. The break created a siphon that sucked the pesticides back into the water system through the farmer's hose.

As a result of exposure to contaminated water, some persons experienced nausea, acute stomach burning and pains, profuse sweating, diarrhea and shortness of breath. Others suffered lip sores, burning gums and leg cramps.

This incident has resulted in a class action lawsuit seeking unspecified damages for medical expenses, lost earnings, pain and suffering, cost of testing the water and any loss of property values.

The lawsuit charged the water company did a poor job of notifying its customers of the contamination. The suit states "The affected area was much larger than the area in which the residents were warned by the water company. We know this because the water turned blue in homes of many of the people who were not warned by the water company." Some customers are known to have used the water for three or four days before either reading about the contamination in the paper or being warned by a neighbor.

The suit faults the water company for failing to warn customers, failing to test the water after contamination, not decontaminating the water and not having devices to "prevent contamination by back-flowing water."


1995-002

DATE OF OCCURRENCE: July, 1995

LOCATION: Yakima, Washington

SOURCE OF INFORMATION: Yakima Herald-Republic, August 1, 1995

SUMMARY: A cross-connection permitted untreated irrigation water to flow into domestic water lines causing 11 cases of giardiasis.

DETAILS:

Eleven cases of giardiasis were confirmed in a Yakima neighborhood after a cross-connection permitted untreated irrigation water to flow into domestic water lines.

The contamination is believed to have occurred when a business tapped into an irrigation line without installing a workable backflow device. The cross-connection was not discovered until about a month after the incident.

Residents in the area began complaining about cloudy water soon after the cross-connection occurred. Initially the problem was suspected to be a main line damaged during a construction job. Repairs were made, lines were flushed and the situation initially appeared to improve.

Residents in the area continued to complain about cloudy water, and an unknown number were stricken with bouts of diarrhea, nausea, cramping and other problems.

Domestic water systems are not typically tested for Giardia, the parasite that causes giardiasis, a flu-like intestinal ailment sometimes known as Beaver Fever.

Tests for coliform bacteria revealed no problems, those tests, however, are typically conducted at well heads, not within the distribution system where the alleged illegal cross-connection occurred.


1995-003

DATE OF OCCURRENCE: October, 1995

LOCATION: Tacoma, Washington

SOURCE OF INFORMATION: Tacoma Public Utilities

SUMMARY: An air compressor connected to the # 1 test cock of a DCVA on a landscaped irrigation system pumped air into the water distribution system.

DETAILS:

To winterize a landscape irrigation system at a fast food restaurant, a contractor connect an air compressor to test cock #1 of a double check valve assembly. The contractor thought the irrigation system was isolated by a closed gate valve upstream from the backflow assembly. The contractor, upon questioning, stated that the gate valve used to isolate the irrigation system did not close properly. Air was pumped through the service connection into the utility's 16-inch water main on the street. The distribution system pressure was approximately 40 psi. The compressor operated at 120 psi.

Several businesses experienced a lack of water and/or air in the water for periods of time ranging from 20 minutes to 6 hours. Dirty water was also a problem due to the disturbance of sediment in the water mains.

Corrective action consisted of water main flushing through fire hydrants.


1995-004

DATE OF OCCURRENCE: February, 1995

LOCATION: Spokane, Washington

SOURCE OF INFORMATION: Spokane Water Department

SUMMARY: Pink water was reported in a high rise multipurpose building; the result of a cross connection with a heating/cooling system pump.

DETAILS:

On February 1, 1995, the Spokane Water Department received a call from a customer stating that the water in the basement and on the 1st floor at the drinking fountain was pink in color. The customer manages a high rise multipurpose building.

Upon the inspection made of the building, it was noted that the building had oil cooled pumps for heating and cooling, with a water backup for emergencies.

On this date, a maintenance person operated the valve which allowed the oil, at the time that the pump was running, to overcome the pressure inside the building. The building was protected by double check valve assemblies on both the domestic and the fire service.

The customer has since disconnected this water line to the pump and has installed a reduced pressure backflow assembly in line to the maintenance facility.


Backflow Incident Report Form

There are many backflow incidents which occur that are not reported. This is usually because they are of short duration and are not detected, the customer is not aware they should be reported, or it may not be known to whom they should be reported.

The PNWS-AWWA Cross Connection Control Committee is making an effort to bring these incidents to the attention of water purveyors and the public. If you have any knowledge regarding incidents, please fill out a copy of this form and return it to the committee, c/o the individual named on the reverse side. In addition, the state or provincial health agency should be notified.

Reporting Agency: ____________________________________ Report Date: _____________

Reported By: _________________________________________ Title: ___________________

Mail Address: ________________________________________ City: ____________________

State: ________________ Zip Code: ____________________ Telephone: _______________

Date of Incident: ___________________ Time of Occurrence: _______________________

General Location (Street, etc.): ________________________________________________

Backflow Originated From:

Name of Premise: __________________________________________________________

Street Address: ________________________________ City: ____________________

Contact Person: ________________________________ Telephone: _______________

Type of Business: _________________________________________________________

Description of Contaminants:

(Attach Chemical Analysis or MSDS if available)

_________________________________________________________________________________

_________________________________________________________________________________

Distribution of Contaminants:

Contained within customer's premise: Yes: _____ No: _____

Number of persons affected: _____________

Effect of Contamination:

Illness Reported : ________________________________________________________

Physical irritation reported: _____________________________________________

Backflow Incident Report Form

Page 2

Cross Connection Source of Contaminant

(boiler, chemical pump, irrigation system, etc.)

_________________________________________________________________________________

_________________________________________________________________________________

Cause of Backflow:

(main break, fire flow, etc.)

_________________________________________________________________________________

_________________________________________________________________________________

Corrective Action Taken to Restore Water Quality:

(main flushing, disinfection, etc.)

_________________________________________________________________________________

_________________________________________________________________________________

Corrective Action Ordered to Eliminate or Protect from Cross Connection:

(type of backflow preventer, location, etc.)

_________________________________________________________________________________

_________________________________________________________________________________

Previous Cross Connection Survey of Premise:

Date: _____________________________ By: ______________________________________

Types of Backflow Preventer Isolating Premise:

RPBA: _____ RPDA: _____ DCVA: _____ DCDA: _____ PVBA: _____ SVBA: _____

AVB: _____ Air Gap: _____ None: _____ Other Type: ________________

Date of Latest Test of Assembly: ________________________________________________

Notification of State [Provincial] Health Department:

Date: _________ Time: __________ Person Notified: ___________________________

Attach sheets with additional information, sketches, and/or media information, and mail to: PNWS-AWWA

c/o George Bratton

1252 S. Farragut Drive

Coupeville WA 98239