About backflow

Additional Information


What is Backflow?

In supplying a community with water, it is intended that water go from the main to the service line, through the water meter and into the building. However, when a backflow incident occurs, the flow of water goes from the buiding to the water main. When backflow is present, water goes in the reverse direction of flow causing water to go from the building back into the water main. If there are any contaminants present, major illness can occur in an entire community.

How Do We Prevent Backflow?

Backflow assemblies are used in preventing backflow from occurring. These assemblies have check valves designed to close, and in some cases, open in order to prevent water from going in the reverse direction of flow. These assemblies have been used for years to prevent backflow and are very important in protecting our water system. However, they are not infallible and must be tested at least once a year in order to verify they are in proper working condition. It has been said that 1 in 10 backflow assemblies will fail while being tested.


Who Can Test and Repair Backflow Assemblies?

Individuals who have been trained and have passed examinations from the State of Washington to be certified can become backflow testers. These individuals, once they have passed all Washington State testing requirements, can then test all backflow assemblies.  Repairs can only be made on backflow assemblies located outside of a building. For assemblies located inside a building, repairs can only be made by a backflow tester if he or she has a specialty plumbers license from the State of Washington.