Double Check Valve Service
Double check valve service covers double check valve assemblies (DCVA) — the backflow preventers used for low-hazard connections — including installation, annual testing, and repair. FlowFast Plumbing connects you with an independent local plumber who verifies the device suits your hazard level, keeps it tested and compliant, and rebuilds worn check modules when readings fall out of spec.
- Connected with an independent local pro — never a call center queue.
- Part of our Backflow Prevention Testing & Installation services — explained up front.
Parent service
Backflow Prevention Testing & InstallationBackflow test due? What backflow preventers do, testing requirements, and how to get connected with an independent local plumber.
View all Backflow Prevention servicesA double check valve assembly contains two independently acting check valves in series, with shutoff valves and test cocks for verification. It is the standard choice for low-hazard cross-connections — situations where backflow would be a nuisance or aesthetic problem rather than a health emergency, such as certain fire sprinkler lines and some irrigation setups. Because it has no relief valve, a DCVA discharges nothing during normal operation and can be installed in more locations than an RPZ, though it must never be used where the hazard involves chemicals or serious contaminants.
Through FlowFast Plumbing, an independent local plumber confirms that a double check assembly is actually the right device for your connection — using the wrong type is one of the most common compliance mistakes — then handles installation, the yearly gauge test of both checks, and rebuilds when a check valve stops holding. The pro also watches for the quiet failure mode of these devices: with no relief valve to signal trouble, a DCVA can fail silently, which is exactly why the annual test matters so much for this assembly type.
Warning signs
Signs you need this service
- Your water utility's notice names a double check valve assembly as the required device for your connection, with a deadline for installation and testing.
- The annual test shows one of the two check valves failing to hold its pressure differential, meaning the assembly no longer provides its designed redundancy.
- You are adding or modifying a fire sprinkler line or irrigation connection that your utility classifies as low hazard, calling for DCVA protection.
- An existing double check assembly shows corroded test cocks, weeping shutoff valves, or check modules that have been rebuilt so often the body is suspect.
What to expect
The process, step by step
Verification: the pro confirms the connection is genuinely low hazard and that your utility accepts a double check assembly for it.
Testing or installation: for existing devices, both checks are gauge-tested; for new ones, the assembly is installed with shutoffs and test access.
Service: failed check modules, springs, and seals are replaced with parts matched to the model, and seats are cleaned of debris.
Documentation: passing readings are recorded on the test form and the report is filed with your water utility where required.
Prevention
How to avoid this problem
- Never substitute a double check where the hazard calls for an RPZ — the pro confirms the correct device type.
- Test every year, since a DCVA gives no visible warning like a discharging relief valve when a check starts to fail.
- Keep test cocks operable and free of corrosion so each annual test can actually be performed without delays.
Frequently asked questions
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