Backflow prevention assemblies are devices designed to prevent water from flowing back into the public water delivery system.

Yes, backflow prevention assembly testing is required, at minimum, on an annual basis by a certified tester. A list of certified testers can be found below. Costs for testing varies based on many factors. Some testers charge per test, some charge an hourly rate. Each tester/business determines their own pricing. You might expect to see prices in a general range of $85-$200 per assembly (estimate as of March 2023). If your assembly fails or needs repairs, expect additional charges.

To protect customers receiving water from the Mammoth Community Water District from potential water contamination.

Any location where there is actual or potential uncontrolled cross-connections. Common examples of potential cross-connections locations include:

•      Irrigation systems (residential, commercial and public)
•      Fire Sprinkler Systems
•      Swimming pools and spas
•      Hydronic systems (common example in Mammoth: radiant heating)
•      Hose Bibs

Due to our mountainous environment (large elevation changes) we have increased chances of backpressure. Furthermore, our water supply is limited to our basin and cannot be imported. MCWD follows the recommendations from the State of California Health and Safety Code. Lawn irrigation systems are considered a high-risk for cross contamination because a backflow incident could introduce fertilizers, pesticides and other lawn chemicals (as well as insects and animal waste) into the community’s drinking water, which could be lethally hazardous.

MCWD will grant a one year waiver from the testing requirement if the property owner decides not to utilize their irrigation system. If the property owner decides to discontinue use of their irrigation system, they must remove the assembly, cut and cap the irrigation system to be removed from the requirement going forward. An inspection of the removed and capped system is required.

Code of Federal Regulations, Safe Water Drinking Water Act of 1986

Code of California Regulations Title 17 and Title 22

California Fire Code: State of California

State of California Health and Safety Code Section 13114.7