05/06/2026
A leaking temperature & pressure relief valve is usually a symptom — not the actual problem.
I get called to a lot of homes where a T&P valve has been “replaced” multiple times, especially during home sales after an inspection report. In many cases, the valve is doing exactly what it was designed to do: relieve excess pressure from the water heater.
The real culprit 9 times out of 10? A failed or improperly charged expansion tank.
Most expansion tanks come out of the box pre-charged to around 40 PSI, but many homes in Sioux Falls, Tea, and Harrisburg run anywhere from 50–80 PSI. If the tank pressure doesn’t match the home’s incoming water pressure, the system can’t absorb thermal expansion correctly — and the T&P valve starts relieving pressure.
Quick homeowner tip:
• Tap on the expansion tank. If it sounds solid all the way through, it has likely failed.
• Look for a PSI marking in Sharpie from the installer (example: “65 PSI” with install date). A properly installed tank should be charged to match your home’s water pressure.
Replacing the relief valve over and over without checking the expansion tank is like changing a smoke detector battery while the house is still on fire.
I believe in fixing the cause — not just the symptom.
— Austin Wolf LLC
Licensed Master Plumber
605-214-7701