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MCWD Groundwater Sustainability Agency

Cross-Connection Control Program

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The District enforces the Cross-Connection Control Program which helps protect the quality of water that is served to its customers. The District has performed several cross-connection surveys within its service areas. Where a degree of hazard has been identified, a backflow prevention device(s) must be installed and maintained to comply with Title 17, California Code of Regulations, Federal Safe Water Act of 1974 and the District's water code. Backflow prevention assemblies are essential as they prevent potential contamination of the drinking water from backflow or back-siphonage conditions.

To view the regulations, please click here.

To view MCWD's code, please click here.

Questions and Answers About Cross Connections & Backflow

A cross-connection is an actual or potential connection between the potable drinking water supply and a source of contamination or pollution. At the District, cross-connections must either be properly protected or eliminated entirely.

An example of a cross-connection is a garden hose running while lying in a water source, like a pool or other form of non-potable liquid. If the pressure drops in the distribution system, using a garden hose without backflow prevention can pollute or contaminate a water system from back-siphonage.

The undesirable reversal of flow of water or mixtures of water and other liquids, gases or other substances into the distribution pipes of the potable supply of water from any source or sources.

There are 2 types of backflow events.

  1. Backsiphonage — Caused by a negative pressure in the water system that causes water to flow backwards.
  2. Backpressure — Occurs when the downstream pressure is greater than the upstream pressure.

Anywhere there is a potential for contamination or pollution of the drinking water system, a backflow prevention device is required. Depending on the degree of hazard, one of our Cross-Connection Specialists may require the following:

  1. Double-Check Detector Assembly (DCDA)
  2. Double Check Valve Assembly (DC)
  3. Reduced Pressure Principle Assembly (RP)
  4. Reduced Pressure Principle Detector Assembly (RPDA)
  5. Spill-Resistant Pressure Vacuum Breaker Assembly (SVB)
  6. Pressure Vacuum Breaker Assembly (PVB)
  7. Atmospheric Vacuum Breaker Assembly (AVB)
  8. Air Gap (AG)

Backflow Testing

Backflow prevention assemblies in our service area must be tested annually, when a device is newly installed/ repaired, or if it is actively leaking. The backflow test itself only takes a few minutes and ensures that each part of the device is operating correctly. Only American Water Works Association (AWWA) certified testers may perform testing and submit test results. Testers must report all tests, including any repairs and replacements in a timely manner.

  • To view a list of approved backflow testers in our area, please click here.
    Any tester not on this list must register in our backflow portal and be approved prior to submitting any testing information.
  • If you are a tester and have questions about the portal and need a how-to guide, please click here: Backflow Testers | SwiftComply Help Center.
  • If you are a tester and need to submit testing information, please report results in our backflow portal here: https://marinaca.c3swift.com/.
  • Customers that receive annual notices for testing and have questions regarding backflow should either call (831) 883-5940 or (831) 883-5952, or can e-mail backflow@mcwd.org
Cross-Connection Control Program