Backflow Prevention & Testing

Backflow Prevention Device, Valve Assembly in AustraliaBackflow Prevention

To protect the public water mains from potential contamination by non-potable "used water" that could be drawn in from the private customer, the City requires installation of a backflow prevention device on new services.


All installed devices must be tested annually by a certified backflow prevention tester and immediately repaired if necessary. During backflow testing, a certified plumber will open and close the valves of the backflow prevention device or assembly to make sure it is functioning as it should. The plumber will assess the valves for leakage, gauge movement and other telltale indicators of a malfunction.

If the valves are working correctly, you'll be all set - if not, the plumber can most likely do some quick repairs to keep your home's water safe and clean. Notice letters are sent to customers each year regarding this testing requirement.

Additional Notifications for Inactive Devices

In the last year, we've made some significant investments to our systems. In the new system we have the ability to differentiate between devices that are inactive (temporarily turned off) versus replaced (removed and replaced with a new device).

Because of this new capability, this year you may have received additional letters with testing forms. With these new forms you are helping us update our systems when your tester reviews your system and notates that the other devices are no longer in service and thus "replaced". There should be no charge for this service.

Thank you for your assistance in make sure our systems are properly updated. If you have any questions or concerns please contact us by email or phone at the information in the following.


For more information, call the Administrative Services Department at 707-665-3631 or email Water Division.