Most commercial properties are required to have a backflow assembly tested every year by a certified tester. New Pro tests, repairs, and installs backflow preventers across the Westside — and files the paperwork your water agency needs. Flat-rate.
Written bySteven Lockhart
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Reviewed byMiguel Lopez, Owner & Licensed Plumber, New Pro Plumbing (CSLB #974600)
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Last reviewedJune 2026 · 7 min read
Quick Answer
Backflow happens when contaminated water reverses into the clean supply, and a backflow preventer stops it. Most commercial properties must have their assembly tested annually by a certified tester and the results filed with the water agency. New Pro tests, repairs, and installs backflow assemblies and handles the paperwork. Flat-rate.
Backflow testing protects the drinking water supply, and for most commercial properties it is a legal requirement, not an option. This page is part of our commercial plumbing coverage across West Los Angeles. The principle comes from the U.S. EPA’s cross-connection control program: wherever the clean supply connects to something that could contaminate it — irrigation, a boiler, a process line — a backflow preventer must stand between them, and it must be proven to work each year.
Backflow is the unwanted reverse flow of water from a property back into the public drinking supply, which can carry contaminants; a backflow preventer is the assembly that stops it, and annual certified testing confirms the assembly still works.
A cross-connection is any point where the clean supply could meet a contaminant if flow reversed — an irrigation system that could siphon back fertilizer and soil, a boiler with treatment chemicals, a commercial process line, even a hose bib left in a tank. A pressure drop — from a main break or heavy demand — can pull that contaminated water backward. The preventer blocks it; the annual test proves the preventer still seals.
Water agencies require certified annual testing of backflow assemblies and the filing of results. Miss it, and you may get a compliance notice or, in some cases, face a shutoff. We test with calibrated gauges, document the result, and file it with your agency — and if the assembly fails, we repair or replace it and re-test, so you end the visit in compliance rather than on a notice.
Most commercial properties must have each backflow assembly tested every year by a certified tester, with results filed to the water agency. We perform the test with calibrated equipment, document it, and submit it — so the requirement is met without you chasing the deadline.
Our how backflow testing works guide explains the test itself, and our business backflow requirements guide covers who needs it and when.
Backflow test due, or got a notice? We test and file.
Call (310) 663-7666If an assembly fails its test — worn check valves, a failed relief valve — we repair it and re-test so you end up compliant. When an assembly is beyond repair or a property needs one installed, we size and install the correct type for the hazard level and connection.
We also identify cross-connections that need protection, so a property that should have a preventer and does not gets one before it becomes a compliance — or contamination — problem.
The Bottom Line
Backflow testing protects the drinking supply and, for most commercial properties, satisfies a legal requirement. New Pro tests with calibrated gauges, repairs or replaces failed assemblies, and files the certified results with your water agency — so compliance is handled, not scrambled. Flat-rate.
Backflow is the reverse flow of water from your property back into the public drinking supply, which can carry contaminants — fertilizer, chemicals, or worse — if pressure drops. A backflow preventer stops it. It matters because it protects everyone’s drinking water, which is why testing is legally required for most commercial properties.
Annually, in most jurisdictions, by a certified tester, with results filed to your water agency. Some hazard levels or agencies require more frequent testing. We track the schedule for our clients so the test happens on time rather than after a compliance notice arrives.
You may receive a compliance notice from your water agency, and in some cases continued non-compliance can lead to a water shutoff. Staying current is straightforward on a schedule — we test, document, and file so the deadline is met without you tracking it.
Most commercial properties, and any property with a cross-connection — irrigation systems, boilers, fire-suppression systems, commercial process connections, and similar. Your water agency determines the requirement based on the hazard. We can assess your property and tell you what applies.
Yes. We perform the certified test with calibrated equipment, document the result, and file it with your water agency. If the assembly fails, we repair or replace it and re-test, so you finish the visit in compliance with the paperwork submitted.
A failure usually means worn check valves or a failed relief valve. We repair the assembly and re-test on the spot where possible, or replace it if it is beyond repair. Either way you end up with a working, compliant assembly and a filed test result.
This page was written by the New Pro Plumbing content team and reviewed for technical accuracy by Miguel Lopez, owner and California-licensed plumber (CSLB #974600). Guidance follows U.S. EPA, U.S. Department of Energy, and California agency sources where cited. Any figures reflect New Pro Plumbing's typical practice and West Los Angeles conditions, not a quote — we confirm pricing in writing before any work begins.
What’s new: June 2026 — first publication.
Most commercial properties are required to have a backflow assembly tested every year by a certified tester. New Pro tests, repairs, and installs backflow preventers across the Westside — and files the paperwork your water agency needs. Flat-rate.
