Backflow Prevention Requirements

Did you know that the District requires a RPP backflow protection device at all properties?

“Backflow” is a term the District uses to describe the undesirable reversal of flow of water or mixtures of water and other contaminating substances back into the public drinking water system, which may occur due to back pressure or back siphonage.  A reduced pressure principle (RPP) backflow prevention device is a testable and repairable in-line assembly that is used to keep potentially contaminated water from entering the District’s drinking water distribution system during a backflow event.

In layman's terms, it's essentially a device that stops water from flowing backward from your pipes into the public water supply.

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Typical backflow prevention device installation

The State of Califorina recently updated its requirements regading the prevention of backflow into public water systems.  As a result, the District included these requirements in its Title III – Water System Management Code (“Title III”).

Of particular note:

  1. Title III Section 3.07.010 requires that all new and existing water service connections from the District have a RPP backflow prevention device installed.
  2. Title III Section 3.07.300 states that it shall be customer’s responsibility, at their own expense, to provide and install a new RPP backflow prevention device in accordance with District standards at a location approved by the District.
  3. Installation must be performed by a licensed plumbing contractor and is subject to District approval. The customer will retain full ownership and responsibility of their RPP backflow prevention device.

Acceptable RPP backflow prevention devices are:

  1. Watts Model 009M2; or
  2. Watts Model 009M3; or
  3. Wilkins Model 975XL; or
  4. Wilkins Model 975XL2; or
  5. Equivalent model to those listed above, with review and approval by the General Manager.

Installation Requirements:

A RPP backflow prevention device needs to be located as close as practical to the user's connection and installed a minimum of 12 inches above grade and not more than 36 inches above grade measured from the bottom of the device and with a minimum of 24 inches side clearance.  The residential water supply must have a minimum separation to any OWTS as specified in the District’s Title IV – Onsite Wastewater Management Code.

Once a device is installed, it must be tested by a certified RPP backflow testing specialist within 24 hours and annually thereafter, with all results immediately submitted to the District.  You are not required to use the District, but the District does provide backflow testing services so please contact us to schedule.  Otherwise, a list of certified backflow testing specialists is available here:  https://stinsonwater.org/learning-center/professional-services-directory/

Questions?

Please contact the District office at (415) 868-1333, or email at: info@stinsonwater.org. Thank you in advance for your assistance in keeping our public water system safe!

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