The City of Wilsonville supplies drinking water to the community that meets all EPA and Oregon Health Division requirements for public health and safety. Although the water that reaches Wilsonville homes and businesses is safe, it can be contaminated when non-potable water back flows into the potable water supply. Although most modern water-using fixtures and appliances have built-in backflow prevention features, there are some situations where a backflow prevention assembly is needed.

Examples of these situations include:
  • Boilers
  • Fire sprinkler systems
  • Solar water heaters
  • Spas
  • Swimming pools
  • Yard irrigation systems
Backflow prevention assemblies can be installed for these fixtures, on the owner's piping system, to keep non-potable water from back flowing into the owner’s or the city’s water system.

Examples of backflow prevention assemblies include:
  • Atmospheric vacuum breaker
  • Double check valve assembly
  • Pressure vacuum breaker
  • Reduced pressure backflow assembly
BackFlow Prevention Device Installation
Homeowners and contractors will need to obtain a plumbing permit to have any backflow system, including atmospheric vacuum breakers (AVBs), installed on any private waterline system, even if the work is performed by the individual owner.

Annual Testing
The city administers a Backflow Prevention Program to ensure that backflow prevention assemblies are installed where necessary and tested upon installation and annually thereafter by an Oregon Health Division certified tester. This program is required by state law and city code, chapter 3.1 to ensure drinking water quality. It is the responsibility of the property owner to have backflow prevention assemblies installed where necessary and tested annually.

Since most residential backflow prevention assemblies are used for irrigation systems, the deadline for testing of residential assemblies is June 30 to coincide with the start of irrigation season. For commercial accounts, the deadline for testing is the last day of the month in which the assembly was installed. Atmospheric vacuum breakers (AVBs) are excluded from this annual testing requirement. The Public Works Department notifies property owners by mail prior to their annual testing deadline. For property owners’ convenience, the City of Wilsonville maintains a list of certified backflow prevention assembly testers in the area.

If you have a backflow prevention assembly on your property, please do your part to maintain a safe drinking water supply for yourself and everyone in Wilsonville. Make sure your assembly is tested annually if required and, if needed, make any repairs immediately. Once installed and properly maintained, backflow prevention assemblies help keep the water you drink safe.

Removing a Backflow Device
You must still have your backflow assembly tested annually regardless of whether your irrigation system is actively in use or not. If it is still physically connected then it must be tested. Simply turning the water off to your irrigation system does not mean you have removed it. There must be a physical separation (gap/break) between your irrigation system and the main domestic water line.

A plumbing permit is required to remove any backflow prevention assemblies and the owner will need to have the city perform an inspection in order to have the backflow officially removed from city records.

Certified Backflow Tester Requirements
For backflow testers wanting to test, repair, or replace backflow devices within the City of Wilsonville, testers will need to complete the Wilsonville Backflow Testers Requirements Form and return it to Public Works.