Backflow and Cross-Connection Prevention

If you are a property owner with an in-ground sprinkler system or private well, state and local laws 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 and 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 Law (WAC 246-290), and City of Vancouver Ordinance (14.04.140 and 14.04.155). These laws require that all irrigation systems have approved backflow protection. A plumbing permit is also required when installing an irrigation system. Without proper backflow protection, your irrigation system could endanger the health of your family, neighbors, and others in the community who are using the public water system.

Improper installation of a state-approved backflow prevention device or failure to meet testing requirements are grounds for termination of water service. The three state-approved backflow assemblies that follow are required to be installed per City of Vancouver 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)
  • Reduced Pressure Backflow Assemblies (RPBA)
Note: The atmospheric vacuum breaker is the only backflow prevention device that does not require annual testing.

On-site water wells
If you have an on-site well and would like City of Vancouver water service, you must first comply to Washington state law (WAC 173-160 and WAC 246-290), and Vancouver Municipal Ordinance (14.04.140 and 14.04.155), 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 Vancouver Standards Specifications. This backflow prevention device must be protected from freezing.
  • If you choose to abandon your well: Proper abandonment procedures, per Washington state law 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.

Questions about backflow and cross-connection prevention

If you have any questions concerning backflow installations, certified testers or approved backflow prevention device, please contact the Water Quality team by phone at 360-487-8276, or by e-mail

Backflow reports

Customers and testers can submit backflow test reports directly to the City by emailing: