Backflow & Cross-Connection Prevention

Backflow DiagramIf you are a property owner with an in-ground sprinkler system, private well, or pressure sewer, state and local regulations require that you install and maintain a backflow prevention device on your service line and have it inspected yearly by a certified tester.

What is backflow?

Backflow is a flow in reverse from the normal direction of flow in a piping system. It occurs due to a differential pressure existing between two different points within a continuous fluid system; a fluid of higher pressures flowing to a fluid of lower pressure. Backflow may occur due to either "backsiphonage" or "backpressure."

What is a cross connection?

A cross connection is any actual or potential physical connection between a potable water line and any pipe, vessel, or machine containing a non-potable fluid, solid, or gas, allowing possible entry to the water system by backflow. This would include, but is not limited to, sewers, drains, conduits, pools, storage reservoirs, plumbing fixtures, or any other device. The non-potable or unapproved water supply system may contain contaminated liquids, solids, or gases, of unknown or unsafe quality. Bypass arrangements such as jumper connections, removable sections, swivel or changeover devices are considered to be a cross connection.

City & State Requirements Protect Our Community's Water Supply 

Irrigation Systems

If you have or are planning on installing an irrigation system, you must first comply with Washington State Washington Administrative Code (WAC) 246-290, and Washougal Municipal Code (WMC) 13.40. These regulations require that all irrigation systems have approved backflow protection. A plumbing permit is also required by our Community Development Department when installing an irrigation system. Without proper backflow protection, your irrigation system could endanger the health of your family, neighbors, and the community.

Improper installation of a state approved backflow prevention device or failure to meet testing requirements are grounds for termination of water service. The state approved backflow assemblies below are required to be installed per City of Washougal standards, and must be tested by a Washington certified tester upon installation and yearly thereafter:

  • Pressure Vacuum Breaker Assemblies (PVBA)
  • Double Check Valve Assemblies (DCVA)
  • Double Check Detector Assemblies (DCDA)
  • Reduced Pressure Backflow Assemblies (RPBA)

Note: The atmospheric vacuum breaker is the only backflow prevention device that does not require annual testing.

Private Wells

If you have a private well and would like City of Washougal water service, you must first comply with WAC 173-160 and WAC 246-290, and WMC Chapter 13.40, before the city can install water service. Failure to comply with state and local regulations are grounds for termination of the water service. The following regulations must be met before water service begins:

If you choose to keep your well: Installation and testing of a state-approved reduced-pressure backflow assembly (RPBA), per City of Washougal Standards Specifications. This backflow prevention device must be protected from freezing.

If you choose to abandon your well: Proper abandonment procedures, per WAC 173-160, using a licensed well driller. Capping the well or pulling the pump is not proper abandonment and will require installation of a state-approved reduced-pressure backflow assembly device.


If you have any questions concerning backflow installations, certified testers, or approved backflow prevention device please contact the Water Division by phone at 360-835-2662, or by e-mail or

Backflow Reports

Customers and testers can submit backflow test reports directly to the City by email.

Testers with City of Washougal credentials can directly enter the test reports into our electronic system here: 

For assistance with electronic entry: (New link for the attached Tokay SQL Web Test Users Guide in this email)

Backflow Information