Backflow testing for a sprinkler system

Sprinkler pipes sit in soil that can hold fertilizer, pet waste and standing water. If supply pressure drops, for example during a main break or heavy fire-hydrant use, a sprinkler head under water can suck that liquid backward into the pipes. The backflow device is the check that stops it, and an inspection by a trained tester shows it still works. For the wider code context, see our notes on permits and gas piping rules, and for an overview of testing at the house, our page on backflow testing in Long Beach.

What is the backflow device on my irrigation line protecting?

Your drinking water, because irrigation water is not drinking water. A device on the line makes sure water can only move one way, from the supply into the sprinklers, and never from the yard back into the home's pipes. Long Beach Utilities' rules require protection against unprotected cross-connections and allow the utility to shut off service where one exists.

The typical home setup is a pressure vacuum breaker, a brass unit on a riser above the soil with two test ports and a cap that vents when needed. Larger or higher-hazard sites use a double check or a reduced pressure assembly. LBUD's rules say a pressure vacuum breaker is accepted for irrigation under certain conditions, and that assemblies must be made from low-lead materials. Which type your lot needs depends on the hazard and the utility's review.

How often must a sprinkler backflow assembly be tested in Long Beach?

Once a year for assemblies connected directly to the public water system, under Long Beach Utilities' rules, and also after a repair or a failed test. The owner pays for it, uses an approved tester and sends the report to the utility. Testing and repairs are due within 30 days of the annual due date.

The City of Long Beach Health Department runs the Cross-Connection Program and posts a list of testers, a sample test form and a fact sheet. A due-date notice normally arrives from your water provider. If you have not received one but have a sprinkler system with a backflow device, ask your water provider about your schedule. San Pedro and Wilmington buy from LADWP, and the cities next door follow programs of their own, so forms and deadlines can differ.

What happens during a sprinkler backflow test?

The tester attaches a gauge kit to the test ports, shuts the isolation valves in sequence, and measures whether the check valves hold and the vent opens at the right pressure. Results go on a form. A pass is filed with the water provider. A failure leads to cleaning, new seals or replacement, then a retest.

On a pressure vacuum breaker, the check is that air inlet opens when pressure drops, and that the internal check holds. The test takes a short time, and the sprinklers are off while it runs. Mineral debris from hard water or grit from a broken head can foul the seats, a frequent cause of failures. Afterward the plumber explains what was found and whether a repair kit solves it. This is a formal inspection, so keep the paperwork.

When should I schedule the test?

Schedule it when your due date arrives and well inside the 30-day window, not on the last day. Many owners pick early spring so the system is checked before the heavy watering season and any repair is done in time. A failed test needs a retest, which takes more time than a single visit.

Also arrange a test after you install a new assembly, move it, repair it or after a sprinkler head or line is damaged by a mower or a pipe break. A newly installed device normally needs a first check, by the utility or an approved tester, before it counts. If you are installing a sprinkler system for the first time, the plan and the assembly type are reviewed first, and a plumber can help with that.

What does a sprinkler backflow test cost?

Residential tests in California run roughly $90 to $200 per assembly, per a 2026 cost guide that gives a national home average near $143 and a California range of $128 to $279. Pressure vacuum breakers tend to be the cheaper type to test. A repair kit or replacement, plus any permit, is extra. Read these as guides, because the quote is what counts.

Ask the plumber whether the price covers filing the report and what a retest costs if the assembly fails. A site with several devices, such as a lawn system, a separate drip zone and a fire line, may price per device. Business owners with multiple sites can read about commercial backflow testing, and homeowners can use the backflow prevention testing explainer.

What about recycled water sprinkler lines?

Some Long Beach sites irrigate with recycled water, which is kept strictly separate from drinking water. The City Health Department's Cross-Connection Program performs a shutdown test every four years on all sites using recycled water, checking that no connection exists between the recycled and domestic lines.

If your irrigation is recycled, the plumber will not connect it to a drinking-water line, and any change to the plumbing needs approval from the right agency. For questions about recycled water cross-connection tests, contact the City of Long Beach Health Department through its Cross-Connection Program page. Do not alter purple-marked piping or fittings yourself.

Who can test my sprinkler backflow assembly?

Only a tester on the approved list for your water provider, who also files the paperwork. Installing, moving or repairing the assembly is plumbing work, which in California mostly calls for a contractor license; you can search for one on the state licensing board's site. Whether a permit is needed varies with the work and the city.

San Pedro and Wilmington answer to LADBS for permits. If you would like a plumber to line up a test or repair, our quote form is the way in.

Common questions

Will the test eat up my afternoon?

About 15 to 30 minutes per assembly when it is accessible and passes. A failure adds repair time, and a replacement means a longer visit and possibly a permit. Before the tester comes, clear soil, plants and any cover away from the device and keep the sprinkler valves reachable.

What do I check about a tester before booking?

Is the tester on the water provider's list? Does the price include filing the report, and is a retest free or charged? What would a repair cost if the device fails? Contractor licenses can be confirmed with the state board, and the price belongs in writing.

Can the test go ahead without me there?

Not always. The tester needs access to the device and to the sprinkler controller or valves, and the water will go off briefly. If the device is in a locked yard, arrange access and leave a phone number. You will want to receive a copy of the test report afterward.