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.

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

The state of California requires backflow prevention to protect water utilities and customers from potential water contamination.

• Cross-Connection Control Policy Handbook
• 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

MCWD may grant a waiver from the annual testing requirement if the property owner decides not to utilize their irrigation system during that calendar year. The property owner must contact MCWD to request a waiver. A site inspection may be required. When property owners decide to irrigate, a completed test report with a passing result must be submitted to MCWD staff prior to using the irrigation system.