Cross Connection & Backflow Prevention

Backflow Prevention Program

Rancho California Water District is committed to delivering safe, high-quality water to our customers. Our extensive water quality program operates 24 hours a day, 365 days a year, to ensure that the water delivered to our customers is kept free from harmful contaminants.

An important part of our water quality program is the backflow prevention program. When a potable water line is connected to a non-potable line, this is known as a cross connection. Contamination may occur when an undesirable substance flows through a cross connection from a non-potable source, such as a sprinkler system, pressure boosting system, or an unapproved water supply into the potable water system. A drop in system pressure caused by incidents such as water main breaks or high demands such as firefighting can cause back-siphonage. This can happen through a process known as backflow. For an informational video, please view the Backflow Prevention video from American Waterworks.

Backflow Devices

Commercial facilities, industrial facilities, agricultural uses, properties with an auxiliary water supply, parcels with irrigation meters, and multi-family dwellings in Rancho Water's service area are some examples of properties required to have a backflow device. This specifically includes a reduced pressure principle device (RP) backflow assembly, Ordinance 2009-10-1 (PDF).

There are more than 9,000 backflow prevention assemblies on water services in our service area. The State Water Resources Control Board requires each of these assemblies to be tested annually. This testing is done by backflow assembly testers approved by Rancho Water. Customers will receive a reminder notice and a list of the approved backflow testers (PDF) is available online. Failure to have the device tested could result in the termination of service. 


Backflow devices are required to be tested annually from the date of installation, or any time the device has been repaired, replaced, or relocated. This annual test is the responsibility of the customer. If you need to have your backflow device tested, view our list of approved backflow testers (PDF). View or download the necessary test and maintenance report (PDF) (Backflow Prevention Devices). 

If you are installing a new RP device or replacing a failed assembly, please refer to Standard Drawing RW-18 (PDF) for backflow device installation requirements for devices 2 inches and smaller. For RP devices 3 inches and larger, please refer to Standard Drawing RW-19 (PDF).

While single-family residences are not generally required to have a backflow device, you can help prevent backflow contamination by:

  • Not leaving hoses attached or submerged in unsafe water such as fertilizer or cleaning solution
  • Confirming that anti-siphon type irrigation valves are properly installed on irrigation valves
  • Installing a hose bib vacuum breaker
    • Note: Most new homes are already equipped with anti-siphon vacuum breakers. If your home does not have these, they can be purchased at local hardware stores. Installation only takes a few minutes.