How often should you test a water heater TPR valve?
Updated July 2026
Test a water heater's temperature-and-pressure-relief (TPR) valve once a year: lift the lever partway, let a burst of hot water rush out the discharge pipe, then release and confirm it snaps shut and stops. This valve is the tank's last line of defense; if pressure or temperature ever runs away, it opens so the tank cannot burst like a boiler. A seized valve that will not open is a genuine explosion risk, yet the part itself costs only about $20.
What changes the interval
| Your situation | Interval | Why |
|---|---|---|
| Standard tank, 2–4 years old | Test yearly | The valve is young, but sediment can still gum the seat |
| Tank 5+ years old | Test yearly, plan to replace | Mineral scale makes older valves stick or weep |
| Valve weeps or drips after testing | Replace the valve | One that will not reseat must be swapped, about a $20 part |
| High water pressure (over 80 psi) | Add an expansion tank | Constant pressure spikes make the valve dribble and fail early |
| No discharge pipe, or pipe points up | Fix before next test | Code requires a downward pipe ending about 6 inches off the floor |
The cost of skipping it
What skipping it costs: the valve is cheap, the failure is not. If the thermostat sticks and the burner runs away with a seized TPR valve, the tank can rupture violently; documented failures have launched water heaters through roofs. Short of that, a valve stuck partly open wastes hot water and drips onto the floor, while one stuck shut removes all overpressure protection. A new valve is about $20 and 30 minutes of work; the tank behind it is a $1,200 to $2,000+ replacement. See the real cost of a water heater failure.
How to do it (5 minutes · DIY)
- Trace the discharge pipe (it runs from the valve down toward the floor) and set a bucket at its end.
- Make sure nobody is near the outlet; the water is scalding hot.
- Lift the TPR lever about halfway and hold it a few seconds; water and air should gush out the pipe.
- Release the lever and watch it snap fully closed. The flow should stop cleanly.
- If it keeps dripping after a minute, flip it again; if it still weeps, plan to replace the valve.
- Replacing means draining a few gallons, unscrewing the old valve, and threading in a new one with fresh tape.
Knowing the interval is the easy half. OnOtto reminds you at the right interval, and it won't let you snooze it into next year. Tasks persist until they're done, and completing TPR valve tests schedules the next one automatically.
Put this on autopilot, free for 30 daysFrequently asked questions
What is a TPR valve and how does it work?
The temperature-and-pressure-relief valve sits on the top or upper side of the tank with a pipe running down toward the floor. It is a spring-loaded safety valve set to open around 150 psi or 210°F, whichever comes first. If the tank ever overheats or overpressurizes, the valve dumps water to relieve it, because superheated water in a sealed steel tank behaves like a bomb. It is required by code on every tank heater and is the one component you should never cap or bypass.
My TPR valve leaks after I tested it. Now what?
Common and usually minor. Debris under the seat often keeps the valve from reseating after a test; flip the lever open and shut a couple more times to flush it clear. If it still weeps after several minutes, the seat is worn and the valve needs replacing, a roughly $20 part. Persistent dripping without any testing points to genuine overpressure, often from high street pressure or a missing thermal expansion tank, which you should address rather than plug.
Why does my TPR valve dribble even without testing?
A valve that dribbles on its own is telling you system pressure is too high, not that the valve is bad. On a closed system with a check valve or backflow preventer, heating water has nowhere to expand, so pressure spikes each cycle and pushes past the TPR valve. The fix is a properly charged expansion tank, plus a pressure-reducing valve if street pressure tops 80 psi. Keep an eye on your home water pressure to catch this early.