What Is Backflow Testing?

Understanding Backflow and Why It Matters

Water is supposed to flow one way. Into your building, not back out into the main. Backflow is what happens when pressure conditions reverse that flow - a main break nearby, heavy water demand down the street, or backpressure from your own system can all cause it.

When that reversal happens, contaminated water from your irrigation system, fire suppression system, or industrial equipment can get pulled back into the public supply. That's the health hazard. A single failed assembly can affect more than just your property.

Backflow prevention devices are mechanical assemblies that stop the reverse flow. They work - but only if the check valves and relief valves inside them are still functioning. California requires most commercial properties to verify that annually with a certified tester.

Who Is Required to Have Backflow Testing?

California state law and local water district rules require annual testing for most properties that present a potential contamination risk. If you received a notice from your water district, you're already on this list. Properties commonly required to test include:

• Commercial and industrial properties
• Restaurants and food service facilities
• Multi-unit residential buildings (apartments, condos)
• Properties with irrigation systems
• Properties with fire suppression systems
• Healthcare facilities and laboratories
• Car washes and auto service facilities

What Happens During a Backflow Test?

A test typically takes 30 minutes or less. Your water will be shut off briefly while the tester connects pressure gauges and checks each valve. David files your report directly with the water district when it's done. Here's the full sequence:

1. 1Shut off the water supply temporarily (usually 15-30 minutes)
2. 2Connect differential pressure gauges to the assembly
3. 3Test each check valve and relief valve for proper function
4. 4Record the test results on an official form
5. 5File the test report with the local water district
6. 6Repair or replace any failed components if needed