Recent Incidents and Articles

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:
To quickly find a particular incident, click on "edit" on your browser, then click on "find on page".  Type in either the state, year, chemical, or condition.   Then click on "Find Next."  


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) Long 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