Backflow and Cross Connection Control Program

As required by Oregon drinking water regulations, the City of Lake Oswego must require annual testing of backflow prevention assemblies/devices. Tests must be performed no later than July 15 of each year. 

What is a Backflow Assembly Device?

Cross connection contamination of the public water system is the leading cause of waterborne disease in public water systems. In plumbing, a cross connection is created if a water supply pipe is connected to a water source that could contaminate the water supply, such as irrigation systems, fire suppression systems, hot tubs/spas, pools, and private wells. Backflow, or the reverse flow of water from the cross connection, may contaminate the water. 

Backflow assemblies separate drinking water from these non-drinking water sources, playing an important role in protecting the quality of your drinking water. This assembly is a mechanical unit that prevents the non–drinkable substance from being able to flow backwards into your plumbing system and / or back into the public water system, avoiding possible contamination of the water system.

Tests Due July 15 Each Year

Backflow Tests are required to be completed and submitted by July 15 of each year. Please mail or email all backflow test reports to: or City of Lake Oswego, Attn: Backflow, 17601 Pilkington Rd, Lake Oswego, OR 97035.

Please remind testers to check for test cock plugs on devices installed below ground level; they are a City requirement. If any device fails the test, it must be repaired and retested. If more than normal repairs are required on an irrigation system using atmospheric vacuum breakers or a pressure vacuum breaker, those devices shall be replaced with approved double-check backflow devices.

Certified Backflow Testers

Backflow Assembly Testers are required to obtain licensing through the Construction Contractors Board (CCB) or the Landscape Contractors Board (LCB) if they provide their services for a fee. CCB and LCB licenses have not been verified for individuals on this list. Call the CCB at (503) 378-4621 or the LCB at (503) 967-6291 to verify licensing.

This list is not intended to solicit service or recommend backflow device testers. These testers are private individuals or companies. They are not employed by, nor should they be considered agents of, the City of Lake Oswego. The prices quoted by testers are not based on any City or state pricing standard, but are set by the individual testers.

Program Requirements

Oregon Health Division Administrative Rules, Chapter 333, Cross Control Requirements, and City Ordinance mandate that the City undertakes a program of

  • inspecting all users' premises where there is reasonable cause to believe an existing or potential cross connection is located;
  • require approved assemblies be installed where cross connections are found; and
  • ensure all backflow assemblies are tested by a State of Oregon certified tester upon installation and on an annual basis thereafter.

To determine whether a device is required at your location, a City representative must inspect your premises. Please call (503) 534-5674 or email to make an appointment for an inspection if you believe a cross connection is present in your service.

Contact Information

Backflow Testing

Email or Phone 503-534-5674

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