Backflow testing in Los Angeles to meet your annual water department notice

Water normally flows from the street main into your property. If pressure in the main drops, say during a firefighting draw or a main break, water inside your system can be pulled back toward the street. A backflow assembly blocks that reverse flow so irrigation water, boiler chemicals or fire line water can't reach the public supply.

Not every home has one. They're common on irrigation systems, fire sprinkler lines, apartment buildings, restaurants, medical offices and properties with boilers or pools. If you got a test notice, the water department has an assembly on record at your address.

• Reduced pressure principle assemblies for higher hazard connections
• Double check valve assemblies for many fire and irrigation lines
• Pressure vacuum breakers on lawn irrigation
• Assemblies at restaurants, clinics and apartment complexes

The test takes a short water shutoff, usually well under an hour for a single assembly. We close the downstream valve, connect a calibrated differential pressure gauge to the test cocks and check each part in sequence: the first check, the second check and, on a reduced pressure assembly, the relief valve opening point.

Each reading has to fall within the range the testing standard sets. A check that leaks back or a relief valve that opens too early fails. We record the readings, the assembly's make, model and serial number, and submit the report to LADWP or your local water department.

Our article on what happens during a backflow test covers the same steps from the property owner's side, including what to tell tenants about the brief shutoff.

Most failures come from debris and scale. Hard LA water leaves mineral buildup on check seats, and sand or bits of pipe scale from old galvanized mains lodge under the rubber discs. A rebuild with new discs, springs and seals usually brings the assembly back into range.

If the body is cracked, the threads are stripped or parts are no longer made for an old model, replacing the assembly makes more sense than repeated repairs. A replacement needs to be an approved model installed at the right height with clearance for testing. After any repair, we retest and file the passing result.

Larger properties often have several assemblies: a domestic line, an irrigation line and a fire line, each with its own deadline. We test them in one visit where possible and give you a single record of what passed, what was repaired and what's due next year. That's useful for apartment buildings with rotating management.

Restaurants and commercial kitchens usually need the test scheduled around service hours. We can come early in the morning or late at night so the water is off when the kitchen is closed. For other work on the same visit, our commercial plumbing service covers fixtures, water heaters and drain lines.