Why Does My Backflow Preventer Need to Be Tested Every Year?

Backflow Preventers Are Mechanical Devices — They Wear Out

A backflow preventer contains springs, check valves, rubber seats, and diaphragms that are under constant water pressure and experience thousands of pressure cycles every year. Over time, these components deteriorate: springs lose tension, rubber seats develop cuts or deformation, and debris in the water can prevent the internal check valves from sealing properly.

A backflow preventer that looks fine on the outside may be failing internally — and there is no way to know without testing it.

Annual Testing Is Required by Law

Water authorities and municipalities across the country require annual backflow testing as a condition of water service. The test verifies that the device is functioning correctly and preventing backflow as designed. Test results must be submitted to the water authority, typically within 30 days of the test, on an approved reporting form.

If you do not have your backflow preventer tested annually, your water authority may issue a notice of non-compliance and, in many jurisdictions, has the authority to shut off your water service.

What Does the Annual Test Involve?

A certified backflow tester connects a differential pressure gauge kit to the test cocks on the backflow preventer. The technician measures the pressure differential across each internal check valve and relief valve to confirm they are holding within acceptable tolerances. The test takes approximately 15 to 30 minutes per device and requires a brief interruption to your water service.

What If My Device Fails the Test?

If the backflow preventer fails the annual test, it must be repaired or replaced before a passing test can be submitted to the water authority. Failure typically means that one or more internal components have degraded to the point where the device is no longer providing adequate protection.