Why Backflow Preventers Fail
Backflow prevention assemblies are mechanical devices with internal components that are subject to wear and degradation over time. During your annual backflow test, a TCEQ licensed backflow tester measures the performance of each check valve and relief valve against manufacturer specifications. A device fails when any component does not meet the minimum performance thresholds.
The most common reasons for failure include:
Worn check valve seats — The rubber or elastomer seats that create the watertight seal on check valves harden, crack, or become compressed over time. This is the single most common cause of backflow test failures.
Debris on valve seats — Sand, sediment, rust particles, or mineral deposits can prevent check valves from seating fully. Even a small piece of debris can cause a check valve to leak beyond acceptable limits.
Fouled relief valve — On RPZ assemblies, the relief valve can become clogged with sediment or mineral buildup, preventing it from opening at the correct differential pressure.
Spring fatigue — The springs inside check valves and relief valves lose tension over time, reducing the force that holds valves in the closed position.
Freeze damage — In the DFW area, winter freezes can crack internal components or distort valve bodies, causing leaks that lead to test failures.
What Happens After a Failed Test
When a backflow preventer fails its annual test, the following process occurs:
- 1Diagnosis — Your certified backflow tester identifies which component failed and determines the cause. This is typically done immediately during the test appointment.
- 1Repair — In most cases, the failed components can be repaired or replaced on site. Common repairs include replacing check valve seats, cleaning debris from valve seats, replacing springs, and rebuilding relief valves. Atlas Backflow of Texas carries repair kits for all major manufacturers and can complete most repairs during the same visit.
- 1Retest — After repairs are completed, the device must be retested to verify it now meets specifications. This retest is performed using the same gauge equipment and procedures as the original test.
- 1Report filing — Once the device passes the retest, your TCEQ licensed backflow tester files the passing test report with your water utility. The report includes both the original failure readings and the passing retest readings.
Can All Failures Be Repaired?
The majority of backflow test failures can be resolved with on-site repairs. However, there are situations where repair is not practical:
- Severe corrosion — If the device body is corroded to the point where test ports are damaged or internal surfaces are pitted, the entire assembly may need replacement.
- Obsolete devices — Some older backflow preventers have been discontinued by the manufacturer, and repair parts are no longer available.
- Repeated failures — If a device fails repeatedly despite repairs, it may indicate the assembly has reached the end of its service life.
In these cases, Atlas Backflow of Texas can recommend a replacement device, coordinate installation with a licensed plumber, and perform the initial test on the new assembly.
Same Day Repair and Retest
Atlas Backflow of Texas comes prepared to handle failures. We carry a full inventory of repair kits, replacement parts, and rebuild components for all major backflow preventer manufacturers including Watts, Wilkins (Zurn), Febco, and Ames. In most cases, we can diagnose the failure, complete the repair, retest the device, and file the passing report — all in a single visit.
Call (817) 612-6088 or email [email protected] if your backflow preventer has failed its test or needs repair.
