Backflow Testing Answer:
Backflow testing is an inspection that confirms your backflow prevention device is working correctly to stop contaminated water from flowing backward into the public drinking water supply. In Los Angeles County, commercial backflow prevention assemblies must be tested once every year by a technician holding a current Los Angeles County Certified Backflow Tester certification, with results filed with your water provider. Below, we break down what the test actually involves, why LA County requires it, and what happens if you miss your deadline.
What Is a Backflow Prevention Device, and Why Does It Need Testing?
Every commercial building’s plumbing system has points where the clean drinking water supply connects to something that isn’t safe to drink — irrigation lines, fire sprinkler systems, boilers, or process water used in manufacturing or medical facilities. These connection points are called cross connections. Under normal conditions, water only flows one direction through them. But if water pressure drops or reverses — from a water main break, firefighting activity, or a pump failure — water can flow backward, pulling contaminants into the drinking water system. That reversal is called backflow.
A backflow prevention assembly is a mechanical device installed at these cross connections specifically to stop that reversal. Like any mechanical device, its internal seals, springs, and check valves wear down over time. A device can look fine from the outside while failing internally. Testing is the only way to confirm it’s still doing its job.
What Happens During a Backflow Test
A certified tester connects a calibrated differential-pressure gauge to the assembly’s test cocks and checks each internal component under controlled conditions. For a double check valve assembly, both check valves need to hold the required pressure differential independently. For a reduced pressure assembly, the tester also verifies that the relief valve opens correctly — this is the safety mechanism that discharges water rather than allowing contamination to pass through if a check valve fails. The tester also confirms the shutoff valves on either side of the device fully open and close. If every component meets its threshold with no leakage, the device passes. If not, it needs repair before it can be recertified.
How Often Does Backflow Testing Need to Be Done in LA County?
Los Angeles County requires annual testing of every commercial backflow prevention assembly. This requirement comes from California Code of Regulations, Title 17, Article 2, Section 7605(c), and it’s enforced locally by the LA County Department of Public Health’s Cross Connections & Water Pollution Control Program, along with your specific water provider (LADWP, SCV Water, or one of the LA County Waterworks Districts, depending on where your property is located). Testing is also required immediately after a new device is installed, after any repair, and after a device is relocated — not just once a year on a fixed schedule.
Who Can Perform a Backflow Test in LA County?
Not just any plumber can test or certify a backflow assembly here. The technician must hold a current Los Angeles County backflow tester certification, issued and renewed every two years through the county’s Cross Connections & Water Pollution Control Program. One recent update worth knowing: effective July 1, 2026, the State Water Resources Control Board now requires testers working on meter protection backflow assemblies to also hold certification from a state-recognized organization such as AWWA — LA County’s own certification still covers internal assemblies, but no longer covers meter protection devices on its own.
What Happens If You Miss Your Annual Test?
Your water provider tracks testing due dates and sends a reminder notice ahead of time. If a required test isn’t completed and submitted by the deadline, the property typically receives a compliance notice, and continued noncompliance can lead to water service being shut off until the test is completed and the paperwork is filed.
Schedule Your LA County Backflow Test
Anthony’s Backflow has been testing, certifying, repairing, and installing backflow prevention assemblies throughout Los Angeles County for more than 25 years. Our technicians are certified by the American Backflow Prevention Association and licensed by the State of California (Lic #722316), and we handle the paperwork with your water provider so you don’t have to. Call (818) 720-4366 to schedule your annual backflow test.