T&P Leaking After You Tested It
The Short Answer: You lifted the test lever. Now it dribbles. Hard-water scale was the only thing sealing a pitted seat; the lever peeled it off. That is not a dead tank and it is not the same job as a new valve that still weeps. Do not cap it. Flush the discharge, then replace the valve if it will not reseat.
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Search Intent & The Real Problem
A sticker or a plumber said “test the T&P once a year.” You did. A burst of 120°F-plus water hit the pan, then a bead that will not quit. The valve is 150 psi / 210°F. You mechanically opened it. Mineral crust that had been pretending to be a seat is now in the discharge pipe. This page is after the lever. Ongoing dump without a test: overflow discharging. Hard stream: stuck open.
What other guides get wrong
They tell you to pump the lever ten more times “to flush it.” That hammers a pitted seat and can snap a seized stem. They also say a drip after testing is normal for 24–48 hours. A few drops while it reseats, maybe. A bead that fills the pan is a failed seat. And they skip pressure: if the house is 90 psi, testing just advertised a problem that was already there.
Step-by-Step Troubleshooting
Step 1: What you actually did to the valve
| After the test | Meaning | Next |
|---|---|---|
| A few drops, then dry | Seat reseated | Watch. Do not keep lifting |
| Steady drip from the discharge opening | Seat dirty or cut | One gentle flush, then replace if it continues |
| Stream that will not die | Stuck open | Isolate. Never cap |
| Lever stuck up / snapped | Stem seized with scale | Replace the valve. Do not pry it |
| Weep at the threads, discharge dry | You disturbed the NPT joint | Remake the joint — not a seat problem |
- What to look for: Opening vs threads. Pan filling vs a stain.
- Required tools: Paper towel, flashlight. Bucket under the discharge if it terminates in the pan.
Step 2: One attempt to reseat — then stop
- What to look for: Discharge piping the full outlet size, not a kinked 3/8” tube. Lift the lever smoothly to full open for a few seconds so a slug of water can carry grit off the seat, then let it snap shut. Do not bounce it. If it still drips, the seat is finished.
- Required tools: Gloves, a path for hot water, people clear of the pipe.
If the lever is frozen, do not beat it. That valve is already a replacement, and a snapped stem stuck open is a flood. Energy off, cold inlet off if it opens and stays.
Step 3: Make sure you did not just reveal high pressure
- What to look for: Static over 80 psi at a hose bib. Waterlogged expansion tank (Schrader spits water). The test did not create 110 psi; it showed a valve that was already the expansion tank. Same physics as Rinnai T&P.
- Required tools: Hose-bib gauge, tire gauge on the expansion tank.
Fix PRV and expansion or the next new valve weeps too — which is the after replacement article.
Step 4: Replace the valve, not the heater
- What to look for: Matching 150 psi / 210°F T&P, discharge full size, slope to drain, no threads on the outlet, no valve in the run. Tank jacket dry. If the jacket is wet, you have a bottom leak, not a test-lever problem.
- Required tools: Two wrenches, potable dope or a new gasket on the inlet threads only, bucket. Breaker or gas off. Drain a few gallons so the opening is not a fountain — no floor drain if needed.
Do not reuse the valve you just mangled. Dope on the outlet is how you glue it open.
Step 5: Overheat vs a test drip
- What to look for: Steam, faucets hotter than a 120°F setpoint, ECO that will not hold. A test lever did not weld a thermostat closed — but if the discharge is scalding and will not quit, you are in temperature lift. Shut it down. Thermostat burn-up.
- Required tools: Contact thermometer at a nearby faucet. Covers stay on until energy is proven dead.
When DIY Ends: Calling a Licensed Pro
Stop if it streams, the lever snapped, you cannot isolate the tank, pressure is over 80 psi and there is no PRV you can see, or the water is steaming. You may gauge a hose bib and, once, open a free lever to flush. You may not cap the pipe or keep exercising a dripping valve. A licensed plumber replaces the T&P, sets expansion and the PRV, and confirms the tank is not the source.
Frequently Asked Questions
Q: Why is the pressure relief valve leaking after I tested it? A: Lifting the lever stripped mineral off a pitted seat, or the stem did not reseat. A few drops can pass. A drip that continues means replace the valve — after you check house pressure.
Q: How long should a T&P drip after testing? A: Seconds to a couple of minutes while the seat wets and closes. Hours of dripping is a failed seat. Do not wait days, and do not cap it overnight.
Q: Should I test the T&P every year if it always leaks afterward? A: Exercise it only if the discharge is safe and you are willing to replace the valve the same day. In hard water, annual “tests” are how old valves start flooding. Replacement on a schedule is cleaner than a seized lever.