Why is my backflow assembly dripping from the side?

On a reduced pressure principle assembly, discharge from the relief valve usually means a check is not sealing, often because of grit, scale or a worn seal. It is a sign the assembly needs testing and repair, not something to plug. Many assemblies can be rebuilt in place and retested.

Backflow Preventer Testing and Repair

Have the irrigation backflow assembly tested, repaired or replaced and the record filed the way the water provider requires.

Request an estimate(623) 288-0259

What the assembly does and when it is tested

An irrigation system sits in soil, fertiliser and standing water. When a hydrant opens or a main breaks, supply pressure can sag; when a pump or elevation pushes harder on the yard side, the flow can reverse. Either way, water that sat around heads and emitters can travel back toward the drinking supply. A backflow prevention assembly at the irrigation connection holds that water back with spring-loaded checks, and on a reduced pressure principle assembly, a relief valve that opens to discharge water if a check leaks.

Water providers in Arizona run backflow programmes under state rules. EPCOR Water Arizona, for example, requires assemblies to be tested by a certified tester when installed, when cleaned, repaired or overhauled, when relocated, every year, and whenever the regulator asks. The provider decides which properties need an assembly and which type; the property owner arranges the test and the record.

In Sun City the provider is EPCOR's Sun City Water District, whose tariff names a lead free reduced pressure principle assembly for irrigation service wherever one is required.

Repairs, replacement and the paperwork

A failed test usually means a check is held open by grit or scale, a seal has hardened, or a relief valve no longer seats. Most assemblies can be rebuilt in place with the maker's kit and retested the same visit. Replacement makes sense when the body is cracked or frozen, the model is no longer supported, or the unit was stolen or damaged.

The paperwork is part of the job, not an extra. Providers set a deadline for submitting test results and list what the record must contain, typically the assembly's serial number, make, model and size, its location, the test date, any repair, and the tester's name and certificate number. Ask who will file the report and keep a copy. Test steps are not reproduced here; testing is done by a certified tester with a calibrated gauge. For how one provider's tariff applies in practice, see backflow preventer testing in Sun City.

Source: EPCOR Water Arizona, Cross Connection Control, Checked Oct 1, 2026