California · statewide
Backflow testing in California under the state Cross-Connection Control Policy Handbook
Updated · Editorial team; not yet technically reviewed
Short answer
California's State Water Resources Control Board adopted the Cross-Connection Control Policy Handbook in December 2023, and it took effect July 1, 2024. It's mandatory for every public water system and requires backflow prevention assemblies to be tested and maintained annually; your water supplier runs the program and sends the notices.
What California requires or changes
The State Water Resources Control Board adopted the Cross-Connection Control Policy Handbook on December 19, 2023; it took effect July 1, 2024. [1]
Compliance with the handbook is mandatory for all California public water systems, which must run cross-connection control programs. [1]
The handbook requires annual testing and maintenance of backflow prevention assemblies and sets standards for certifying testers. [1]
The State Water Board adopted a revised handbook on June 17, 2025, extending some deadlines and aligning language with existing regulations. [1]
Where homes run into it
- Irrigation systems connected to drinking water, especially with fertilizer injectors.
- Homes with a private well and a public connection, or an auxiliary supply.
- Fire sprinkler systems in larger homes.
- Pools, boilers and other equipment the supplier rates as a hazard.
When the test notice arrives
Your supplier sends the notice, usually with a due date. A certified tester checks the assembly, and the result goes to the supplier on its form or portal. If the assembly fails, it's repaired or rebuilt and retested. Missing the deadline can lead to shutoff of the protected service under supplier rules, so book early in the season. For how a test works, see backflow testing.
Further reading: How backflow happens and which devices homes use.
Common questions
When did California's cross-connection handbook take effect?
July 1, 2024; the State Water Board adopted it on December 19, 2023.
How often do California backflow assemblies need testing?
At least once a year under the handbook, plus after installation or repair.
Who enforces backflow testing in California?
Your public water system, which must run a cross-connection control program under the handbook.
Was the California handbook changed after adoption?
Yes. A revised version adopted June 17, 2025 extended some deadlines and changed wording.
Does every California home need a backflow assembly?
No. Suppliers require one where a hazard exists, such as irrigation, an auxiliary water supply or fire sprinklers.
Who can test a backflow assembly in California?
A tester certified under the standards the handbook sets and accepted by your water supplier.
What happens if my California backflow test fails?
The assembly is repaired or replaced and retested before the result is filed.
Where do California test results go?
To your water supplier, on its form or portal, by the due date on the notice.
Why does a garden irrigation system need backflow protection?
Pressure drops can pull water standing in sprinkler lines, with fertilizer or soil, back into drinking water.
Can a missed backflow test cut off my water?
Suppliers can shut off the protected service under their program rules, so respond to notices on time.
Backflow Testing across California
- Water Heater Replacement in CaliforniaReplacing a water heater in California: the state law requiring earthquake straps, where they go, the seller certification at sale.
- Toilet Installation in CaliforniaCalifornia's fixture law for pre-1994 homes: when a remodel permit triggers toilet replacement, the 2017 deadline and seller disclosure.
- Backflow Testing: the full guideWhat backflow is, which homes and businesses need backflow preventers, how annual backflow testing works, and what happens if a device fails.
- Plumbing in CaliforniaCalifornia's plumbing code, licensing, climate and the cities we cover.
The same service in other states
Sources (1)
- State Water Resources Control Board, Cross-Connection Control Policy Handbook · checked 2026-10-03