Backflow FAQs
Cross-Connection Control Program Frequently Asked QuestionsWhat is a backflow assembly & why do I need it?
A backflow assembly is a safety device required by law to protect the public drinking water system. It is owned by the property owner and is installed on the customer’s private plumbing system to prevent water from flowing backward from the property into the public water supply.
Backflow protection is required because private plumbing systems, such as irrigation or sprinkler systems, can introduce potential contaminants (such as fertilizers, chemicals, or other substances) if water were to flow in the wrong direction.
The most common residential backflow assembly is a double check valve assembly (DCVA), which is typically installed for sprinkler and irrigation systems.
Why is the policy being changed?
We revised the policy so our staff can focus on more urgent water quality programs within the distribution system. The revision was adopted by the Nob Hill Water Board of Trustees in May of 2026.
Other drinking water systems do not test private backflow assemblies for their customers, so we are heading towards that more standardized practice. For local reference, the City of Yakima requires private backflow tests for all private backflow assemblies.
Private testers can complete the test for you and submit the results to us.
Why does this affect my property?
During a backflow test we completed at your property in previous years, your property/assembly was labeled as requiring a special appointment for testing. All current and future properties/assemblies requiring an appointment must obtain a private backflow test under the new revision.
What happens if I don’t get the test completed?
This is an annual requirement from Washington State Department of Health regulations regarding your privately owned backflow assembly. Failure to complete the testing will result in termination of water service until the backflow assembly test report is received in our office.
Who do I call to complete this private test?
Any Washington State certified Backflow Assembly Tester can complete this work for you. On our website, we provide a list of testers who have informed us they would like to test our system.
There may be more options outside of the list we published. We recommend that you call around for the best price.
What if I can’t meet the deadline?
Please schedule your backflow assembly test as soon as possible. If your scheduled test date will occur after the deadline listed in your most recent notice, please let us know.
Where is my backflow assembly?
Your backflow assembly is typically located outside where your sprinkler system starts. In some circumstances, it may be under the house, in the garage, or in a shed. If we included a test report with your recent notice, it may include a location description.
Where can I get more information regarding backflow assemblies and cross-connection control???
The following link is a great source of information: https://www.wawater.com/waterquality/ccc/