Backflow Prevention: Some Cautionary Tales

Backflow prevention is a serious problem. Too often, an unexpected incident at a business leads to contaminated water in the surrounding neighborhoods.

We've found some examples of backflow contamination , and we warn you, these are not pretty tales. Luckily, with proper remediation, most backflow accidents can be managed. But why wait for an incident that is traced to your company? Routine backflow testing and proper backflow prevention systems could have prevented all of the incidents we've included below.

Seattle, Washington - Gray-green, muddy or soapy water was reported in a neighborhood near a large car wash facility. The cause was a broken high-pressure pump. Workers kept the system operating by connection a 2-in diameter hose to the rinse cycle. Unfortunately, this part of the rinse cycle system connected to the car wash's potable water system. The owner repaired the pump, but no one thought to remove the hose. Soapy water was pumped right into the potable water of surrounding homes and businesses. Once the hose was removed, the city was able to flush the water main and limit the contamination. The owner of the car wash installed a reduced-pressure principle back-flow prevention assembly and that ended the risk of a repeat accident.

Cincinnati, Ohio -  A water supply valve at a winery was accidentally left open after workers flushed out a tank. In a later fermenting process, wine backflowed from the tank into the city water mains...and out of the faucets in nearby homes. This happened because the pressure in the wine distilling tank was greater than the pressure in the city water system.

San Antonio, Texas - Improper maintenance activities caused effluent from a wastewater treatment plant to backflow into the plant's potable water system. Luckily, because a reduced-pressure principle backflow-prevention assembly was in place at the water service connection to the plant, the contamination remained only in the plant.

Eugene, Oregon - Superheated water from a boiler in a tire retreading plant backflowed in the city's drinking water system. The hot water contained a boiler treatment compound that melted the PVC pipe to the plant, as well as damaging the city's water main. This incident was caused by two single check valves in an unapproved backflow device that attached to the potable water line to the boiler. With no backflow preventer at the service connection to the plant, city water was immediately contaminated.

Casa, Arkansas - Residential water near a poultry farm became discolored. Backflow from a chicken house was deemed responsible. Antibiotic solutions were being administered to the chickens with water that was in part supplied by the public water system. An improper backflow system was the cause and was replaced. However, the practice of supplying antibiotics and live viruses to fowls in water can be very harmful to humans when the pathogens get into public water. A reduced-pressure backflow prevention assembly should always be installed in these operations.

Fair Lawn and Hawthorne, New Jersey - After a construction crew inadvertently broke a water main during road work, local residents said the water coming into their homes was milky and smelled bad. The water main break had created a siphoning action in the water mains, and when a pest control company employee rinsed a tank that contained a pesticide solution, the pesticides were sucked into the company's potable water system, and then into the public water system. It took several days to flush and disinfect the water mains and plumbing, and local residents and businesses went without water during that time. A backflow preventer was installed at the water connection to the company, and that solved the issue.

FROM THE EPA - no location given

The chief plumbing inspector in a large Southern city was advised by phone  that blood was coming from drinking fountains at a funeral home. Inspections showed that blood had been circulating in the funeral home's potable water system.
The problem was that a hydraulic aspirator--directly connected to a sink faucet- was being used to drain fluids from bodies as part of the embalming process. Water flow through the aspirator created suction used to draw body fluids through a needle and hose attached to the aspirator. When  the aspirator was used during a period of low water pressure, the potable water system at the funeral home, body fluids were drawn into the potable water system instead of flowing out into the wastewater system.