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Backflow Information

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Cross Connection Control Program

State drinking water rules require public water systems to develop and implement Cross Connection Control (CCC) programs in order to protect our water system from potential contamination. As part of a CCC program, backflow prevention assemblies must:

  • Be installed on irrigation systems that are connected to the City's water system. This assembly helps prevent "backflow," which could carry contaminants into the public water system.
  • Must get tested (when installed and annually after that) to make sure they work properly.
  • A Department of Health certified backflow assembly tester must perform and certify testing.
  • Backflow prevention is required in accordance with WAC 246-290-490 Cross Connection Control.

What is Backflow?

Backflow occurs when water or other substances flow in the opposite direction than intended allowing contaminants to enter the public water system or consumer's plumbing. A backflow incident occurs when biological, chemical, or physical contaminants enter the drinking water supply (under backflow conditions) via unprotected cross‐connections. A cross connection is any actual or potential physical connection between a drinking water system and any other non‐potable substance (liquid, solid, or gas). Cross connections can occur at many points throughout a community's water system. Some specific examples of backflow incidents that can occur are:

  • Lawn chemicals backflowing (siphoning) through a garden hose into indoor plumbing and potentially into the distribution system.
  • Carbonated water from a restaurant's soda dispenser entering a water system due to
  • Backflow of chemicals from industrial buildings into distribution system mains.

Water from the customer's system can backflow into the water main when the pressure in the City's water main is lower than the pressure in the customer's system. This can occur when there is a break in the water main or during construction or firefighting activities.

Guidelines for Backflow Assembly Testing

Test reports should be complete, timely, and accurate. Be sure test reports are filled in accurately and submitted to the City of Walla Walla Water Division office as soon as possible after testing. This is for the benefit of the customer, the tester and the City.

Residential tests are due by June 15, 2020. Commercial tests are due by July 1, 2020.

It is the customer's responsibility to ensure a test report is submitted to the City by the due date. Please use the pre‐printed forms mailed to the customers. If you are not able to obtain the pre‐printed forms, a blank form in the City's format may be downloaded from the City's website links at bottom of the page. Either way is acceptable.

NOTE: Tests must be performed by a certified Backflow Assembly Tester. See below for a list of certified Backflow Assembly Testers registered with the City.


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