Keeping Our Water Safe: Understanding Backflow Preventer Test Procedures

Clean drinking water is something we often take for granted. However, protecting our potable water supply from contamination is crucial. This is where backflow preventers come in – essential devices that stop potentially contaminated water from flowing backward into the clean water system.

But simply installing a backflow preventer isn't enough; regular testing is vital to ensure they are working correctly. So, what exactly happens during a backflow preventer test? The specific procedure depends entirely on the type of backflow prevention assembly installed. Here’s a look at the common types and their corresponding tests:

Why Test Backflow Preventers?

Before diving into the types, let's quickly recap why testing is non-negotiable:

1. Public Health: Prevents contaminants (pesticides, chemicals, bacteria) from entering the drinking water supply.

2. Device Assurance: Mechanical devices can fail over time due to wear, debris, or improper installation. Testing confirms they operate as designed.

3. Compliance: Most municipalities and water authorities mandate regular testing (usually annually) by certified professionals.

Common Backflow Preventer Test Procedures

Certified backflow testers use specialized differential pressure gauges to perform these tests. While the specifics can be technical, here's a general overview:

1. Reduced Pressure Zone Assembly (RPZ) Test:

   • Device Type: RPZs offer the highest level of protection, used in high-hazard situations. They have two check valves and a pressure-monitored relief valve in between.

   • Test Procedure: The RPZ field test procedure is the most complex. It involves checking the 2 check valve for tightness, verifying the relief valve opens correctly before the pressure differential between the check valves drops too low, and finally, checking the 1 check valve for tightness.

2. Double Check Valve Assembly (DCVA) Test:

   • Device Type: DCVAs consist of two independent check valves. They are used in low-to-medium hazard situations.

   • Test Procedure: The DCVA field test procedure is simpler than the RPZ test. It focuses solely on confirming that both the 1 and 2 check valves seal tightly against reverse pressure.

3. Pressure Vacuum Breaker (PVB) Test:

   • Device Type: PVBs protect against back-siphonage (negative pressure) but not backpressure. Often seen on irrigation systems. They have one check valve and an air inlet valve.

   • Test Procedure: The PVB field test procedure verifies two main things: that the air inlet valve opens correctly when pressure drops (preventing a siphon) and that the check valve seals tightly against potential backflow.

4. Spill-Resistant Vacuum Breaker (SVB) Test:

   • Device Type: Similar to a PVB but designed not to spill water during normal operation or testing. Also protects against back-siphonage.

   • Test Procedure: The SVB field test procedure is very similar to the PVB test, checking the proper functioning of the air inlet and the tightness of the check valve.

Who Performs the Tests?

Crucially, backflow preventer testing must be performed by a certified backflow assembly tester. These professionals have the training, specialized equipment, and knowledge to conduct the tests accurately and safely, ensuring your device complies with local regulations.

Conclusion

Regular backflow preventer testing isn't just a requirement; it's a critical step in safeguarding our water quality. Understanding the different test procedures highlights the importance of having the right test performed for your specific device by a qualified professional. Don't delay – ensure your backflow preventer is tested annually to protect your health and your community's water supply.