Backflow Incidents
This page lists some of the backflow incidents that have occurred locally in Greater Victoria, in the Province of British Columbia, in Canada, in the United States and worldwide. In each incident, some type of material entered the water system piping and contaminated the drinking water. It should be noted that many backflow incidents go unreported.
- Backflow Incidents in Greater Victoria
- Backflow Incidents in British Columbia
- Backflow Incidents in Canada
- Backflow Incidents in USA
- Backflow Incidents Worldwide
Backflow Incidents in Greater Victoria
- June 1989 - Victoria, BC - Machine Coolant from Manufacturing Plant. Following a shutdown of a water main for maintenance, a machine coolant was backsiphoned into the potable water piping in a manufacturing plant. Details…
- Nov 1988 - Victoria, BC - Saltwater from Navy Dockyards. 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…
- March 1986 - Victoria, BC - Corrosion Inhibitor from Air Conditioner. 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..
Backflow Incidents in British Columbia
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Jan 1993 - Vancouver, BC - Blue Sanitizer from Toilet. Blue toilet sanitizer water is backsiphoned into potable water system. Details…
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Nov 1987 - Burnaby, BC - Auxilary Water via Temporary System. 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…
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Dec 1986 - Vancouver, BC - Green Water from Commerical Buildings. 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…
- Mar 1978 - Vancover, BC - Corrosion Inhibitor from Boiler System. 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…
- Jan 1978 - Vancouver, BC - Carbon Dioxide from Beverage Machine. 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…
- 1972 - New Westminster, BC - Auxiliary Water from Dual Water System. River water, drawn by an automatic pump, was forced past a check valve into the potable water system of a mill. Details…
Backflow Incidents in Canada
- 2005 - Stratford, ON - Detergents from Car Wash. Spill from car wash contaminates water in Stratford, ON.
- Apr 1992 - Winnipeg, MA - Blue Disinfectant Water from Toilet Tank. A Seniors Residence experiences intermittent "blue colored" water in taps. Details…
- 1992 - Edmonton, AB - Sudsy Water from Pump in Plastics Factory. Employees of a plastic manufacturing company disconnect a vacuum breaker causing backpressure of potassium hydroxide and calsolene oil into the city system. Details…
- Jun 1991 - Edmonton, AB - Super Chlorinated Water from New Main. 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…
- Apr 1991 - Edmonton, AB - Rusty Water from Fire System. 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…
- Oct 1989 - Edmonton, AB - Smell from Fermenting Vessel. A backflow incident contaminated the domestic hot water system in a research lab with a growth nutrient for micro-organisms. Details…
- Oct 1989 - Edmonton, AB - Contaminants from Fire Hose Cabinets. 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…
- Aug 1989 - Edmonton, AB - Brown water from Fire Pump System. 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…
- July 1989 - Edmonton. AB - Glycol from Fire System. 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…
- May 1989 - Edmonton, AB - Brown Water from Fire System. 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.
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- Jan 1989 - Edmonton, AB - Green Dye from Pumped Holding Tank. 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…
- Sept 1988 - Edmonton, AB - Contaminants from Fire System. A faulty wafer check valve permitted the backflow of water from a fire sprinkler system into an office building's potable water system. Details…
- Aug 1988 - Edmonton, AB - Murky Water from Heating System. 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…
- Apr 1988 - Edmonton, AB - Blue Water from Toilet Tank. A watermain break caused cleaning solution in a toilet tank to backflow into the residence potable water system. Details…
- Dec 1987 - Calgary, AB - Chromates from Hot Water Heating System. A watermain break forces chemically treated water into an elementary school's potable water system. Details…
- Aug 1987 - Edmonton, AB - Carbon Dioxide from Drink Dispenser. Failure of a dual check valve on a soft drink dispenser allowed carbon dioxide to enter the water system. Details…
- Jun 1987 - Kitchener, ON - Nickel Solution from Plating Rinse Tank. 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…
- Mar 1987 - Edmonton, AB - Hot Water from Boiler System. 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…
- July 1986 - Winnipeg, MA - Antifreeze from Boiler. A faulty check valve on a boiler permitted the backflow of antifreeze into the potable water system. Details…
- July 1984 - Edmonton, AB - Polypropylene from Heating System. Three leaking check valves at a Light Rapid Transit station allowed polypropylene to enter the water system. Details…
- 1976 - Winnipeg, MA - Fertilizer from Garden Nursery. The backsiphonage of a fertilizer occurred when snow clearing operations knocked over two fire hydrants. Details…
- Oct 1973 - Toronto, ON - Cleaning Solvent from Auto Undercoat Shop. The water piping in an industrial mall was contaminated through the backflow of a cleaning solvent from an automotive coating shop. Details…
Backflow Incidents in USA
- Leeds, IO - Milky Water from Commercial Building. Lack of proper maintenance (no backflow preventer testing??) blamed for air & "milky water" backflow incident scare…
- Missoula - Sewage Connected Improperly. Private contractor mistakenly hooked a residential sewer line into a commercial water line. Details…
- Oct 2005 - Spokane, WA - E. coli from Irrigation System. Boil advisory issued after E. coli found from Backflow during the winterization of lawn sprinkler systems lacking backflow preventers - Seattle Post-
Intelligencer
- Aug 2001 - Delafield, WI- Nitrates from Boiler System. Elementary school students were exposed to high levels of nitrate due to low water pressure and a faulty back-flow preventer valve between the school's drinking water supply and its boiler heating system. High nitrate exposure can cause an oxygen deficiency in blood carried throughout the body. The situation was caused by the installation of the wrong valve by a contractor and the lack of detection of the incorrect valve through the state inspection process.
- Oct 1991 - Southgate, MI - Worms from Irrigation System. Residents found parasitical worms (nematodes) in their water after the atmospheric pressure breaker malfunctioned on a privately owned underground sprinkler system. During a water pressure drop, the vacuum in the system sucked some water from the sprinkler into the city water. The homeowner found worms swimming in the bathtub while filling it to bathe his child.
- October 1979 - Virginia - Insecticide from Garden Hose. The highly toxic insecticide chlordane was back-siphoned into the water system. An extermination company employee had left one end of a garden hose in a barrel of diluted insecticide and the other connected to an external home hose bibb (outside spigot). When the water supply system pressure dropped due to repair work, the chlordane was sucked back through the house into the water system.