Utility data / field results
One utility's annual filing recorded seven failed reduced-pressure assemblies among 483 tested. For California commercial properties, the lesson is practical: annual testing finds problems that appearance alone cannot rule out.
Primary keyword: RP assembly annual testing
Key Takeaways
Annual backflow testing can feel repetitive when an assembly has never caused an obvious problem. The trouble with that logic is that a backflow prevention assembly is mechanical equipment. Its condition is determined by a field test, not by whether the enclosure looks clean or the property has avoided a visible water incident.
A 2024 annual summary report filed by Clackamas River Water gives property owners a useful real-world example. The utility reported 580 reduced-pressure backflow prevention assemblies installed in its system. Of 483 assemblies recorded as tested, 476 passed and seven failed.
That result should not be treated as a national benchmark or applied as a prediction for every California property. It does show why annual testing is more than calendar paperwork. Even in a system where most tested RP assemblies passed, the testing program still found equipment that did not.
A reduced-pressure principle assembly is designed to protect the public water supply where a higher-hazard cross-connection may exist. It uses independently acting check valves and a differential-pressure relief valve, creating a testable mechanical barrier between the property's water system and the public supply.
Because the assembly has moving and sealing components, a passing result cannot be assumed from age, appearance, or last year's certificate. Wear, debris, pressure conditions, damaged components, or a prior repair can change how the assembly performs. Certified field testing measures that performance under a defined procedure.
For commercial sites, RP assemblies may protect irrigation, boilers, process equipment, fire-related systems, medical uses, or other connections identified by the local water supplier. The exact protection and testing requirements still come from the supplier serving the property.
California's April 2026 Cross-Connection Control Policy Handbook says backflow prevention assemblies must be field tested at least annually. It also allows a public water system, the State Water Board, or a local health agency to require more frequent testing for high-hazard premises or assemblies at increased risk of failure.
The handbook also requires testing after installation, repair, depressurization for winterizing, or permanent relocation. If an assembly fails, the public water system must ensure that it is repaired or replaced within 30 days after notification of the failure, unless an allowed extension is part of the system's cross-connection control plan.
For an owner or facility manager, that means the annual due date is only one part of the workflow. A repair can create a retest requirement, and a passing field result may still need to be submitted through the local utility's process.
Keep the entire compliance trail together so a failed test does not become a second missed deadline.
Local water suppliers control the property-specific notice and reporting process, but these planning questions apply broadly.
No. The seven failures came from one utility's annual filing and should not be used as a national or California-wide failure rate. The useful takeaway is that certified testing identified failed assemblies that required follow-up.
California's current policy handbook requires backflow prevention assemblies to be field tested at least annually. A water supplier, the State Water Board, or a local health agency may require more frequent testing for higher-risk conditions.
The next steps normally include repair or replacement, a passing retest, and submission through the applicable water supplier process. California's handbook says public water systems must ensure failed assemblies are repaired or replaced within 30 days after notification, subject to allowed plan extensions.
