What is Backflow?
Backflow is the return of any substance into the system from which it exited. Backflow in the water system is the return of any substance, liquid, or gas, into the potable water system. This can be harmless or extremely harmful depending on the substance in question. There are numerous instances of hazardous substances entering unknowingly into the water system throughout the US.
There are two types of backflow;
Backsiphonage (pulling water out of a system due to a vacuum)
Backpressure (Pushing water out of a system due to elevation differences or a pump)
Backflow devices are considered the second line of defense in protecting our clean drinking water. The first line of defense is the built-in controls to the water system by the water purveyors (companies/departments).
What is Cross Connection?
Cross Connection is the point at which the public water supply can or does meet any other polluting element. The water faucet for a hose is a cross connection point because a polluting element could potentially enter through the hose and continue into the clean water supply.
What is a Backflow Assembly?
A backflow assembly is any device that prevents backflow at a cross connection point. These devices range in complication and size depending on the need of protection, which is determined based on the hazard level.
“Washington State Department of Health, Office of Drinking Water, has the responsibility of regulating public water systems to ensure the water that is supplied to customers of public water systems is safe for human consumption. The purpose of the Drinking Water Regulations is to protect public health of consumers using public drinking water supplies. …
… Owners of backflow prevention assemblies installed to protect the public water system are required to have those backflow assemblies tested by a certified Washington State Backflow Assembly Tester.”
– A Comprehensive Guide to Backflow Assembly Testing in Washington State, Washington Environmental Training Center, April 2007