Annual Backflow Testing in Bellflower: What It Costs and What Happens If You Skip It

Published June 2026 · Bellflower Plumbing Pros

Backflow testing is one of the most predictable annual plumbing costs for Bellflower homeowners with irrigation systems, and also one of the most frequently overlooked. California Health and Safety Code Title 17 requires it. Bellflower-Somerset Mutual Water Company tracks compliance for accounts in its service area. And the underlying purpose — preventing contaminated water from entering the drinking water supply — is real, not bureaucratic. Understanding what the test covers, what it costs, and what the consequences of non-compliance are makes the annual scheduling easier to think about.

The California Title 17 requirement

California Health and Safety Code Title 17, Section 7603 establishes cross-connection control requirements for water suppliers and property owners in California. The practical consequence for Bellflower homeowners is that any backflow prevention assembly installed on a potable water connection where contamination risk exists must be tested annually by a state-certified tester, with results submitted to the water purveyor.

For most Bellflower residential properties, the regulated assembly is the backflow preventer on the irrigation system connection. Irrigation systems represent a contamination risk because they apply water to soil that may contain fertilizer, pesticide, herbicide, and soil bacteria. If the flow direction in the supply connection reversed under certain pressure conditions, contaminated water from the irrigation lines could enter the potable supply. The backflow prevention assembly prevents this reverse flow mechanically. Annual testing verifies the mechanical protection is still functioning correctly.

Bellflower-Somerset Mutual Water Company implements cross-connection control for its service area. BSMWC receives test results from certified testers and maintains records of compliance for accounts with backflow prevention requirements.

What happens during the annual test

The test itself is straightforward. A certified backflow prevention assembly tester connects a calibrated differential pressure gauge to the test cocks on the assembly — small valves positioned specifically for this purpose. The test takes the assembly through a sequence of valve closures that isolates and tests each internal component:

For a pressure vacuum breaker (PVB), the test verifies that the check valve opens at the correct differential pressure and that the air inlet opens when supply pressure drops — the two mechanisms that prevent back-siphonage.

For a reduced pressure zone (RPZ) assembly, the test independently verifies the inlet check valve, the outlet check valve, and the differential pressure relief valve — confirming that each check seat holds at its required differential and that the relief valve opens at the correct differential to discharge any water that passes a failed check.

Readings are recorded on a standardized test report form. A passing result means each component met its required specification. A failing result identifies which component is below spec and must be repaired or replaced before the assembly can be returned to service.

A standard residential test visit takes 20 to 45 minutes including setup, testing, documentation, and preparation of the result submission. We handle the submission to BSMWC directly — the homeowner doesn't need to do anything except schedule the test.

Cost breakdown: test, repair, and replacement

The annual test

A certified residential backflow assembly test in Bellflower runs $75 to $150, covering the tester's time, calibrated gauge equipment, the standard test form documentation, and the BSMWC submission. The range reflects variation by tester and the number of assemblies on the property (a second assembly on the same visit costs less than the first because mobilization time is shared).

Failed assembly repair

If the assembly fails the test, it must be repaired or replaced before the irrigation system can legally operate again. Internal component repair — replacing a worn check valve seat, diaphragm, or spring — is often possible on the same visit when the tester carries appropriate repair parts for the assembly model. Repair adds $100 to $300 depending on which component failed and the parts cost. After repair, the assembly is retested to confirm it passes, and the passing result is documented on the form submitted to BSMWC.

Assembly replacement

Some assemblies are too old, too corroded, or no longer listed by BSMWC for repair parts to be a viable option. In those cases, replacement is appropriate. Assembly cost varies by type:

The distinction between PVB and RPZ is not aesthetic — it reflects the hazard classification of the cross-connection. A standard residential irrigation system without fertilizer injection is typically classified as a low-to-moderate hazard and protected with a PVB. An irrigation system with a fertilizer or chemical injector creates a higher contamination risk and requires an RPZ. If you're unsure which type is appropriate for your system, we confirm the BSMWC-approved assembly type before any replacement work begins.

What happens if you skip the annual test

The consequences of missing an annual backflow test build over time.

BSMWC tracks test submission records for accounts with backflow prevention requirements. When a year passes without a test result on file, the account is flagged as non-compliant. BSMWC's standard procedure is to send a non-compliance notice to the property owner. The notice typically provides a window to schedule and complete the test before additional action.

Continued non-compliance after a notice — particularly in multiple consecutive years — can result in the water company requiring corrective action as a condition of continued water service. In the most persistent cases, service interruption to the regulated connection (such as the irrigation meter) is possible. Water utilities have the authority under Title 17 to enforce cross-connection control compliance to protect the integrity of the distribution system.

Beyond the regulatory consequence, there's the underlying safety purpose. A backflow assembly that hasn't been tested in several years may have failed mechanically — its internal check valves worn below their specified opening pressure, its relief mechanism no longer functioning. An untested assembly provides an unknown level of protection. The annual test is the only way to verify the assembly is actually doing its job.

Frequently asked questions