How to Test a T&P Valve

1. Locate the valve, mounted on the side or top of the tank, and follow its discharge pipe down to where it terminates, usually near the floor.
2. Place a bucket or container under the end of the discharge pipe to catch the water the test releases.
3. Lift the valve's test lever fully to its open position and hold it briefly, then let it snap back down on its own.
4. Watch for a strong, clear discharge of hot water, and sometimes a burst of steam, out of the end of the discharge pipe while the lever is held open.
5. After releasing the lever, confirm the valve reseats completely, meaning the discharge stops fully rather than continuing as a drip or a trickle.
6. If the valve produced no discharge at all, or continues dripping after the lever is released, the valve needs to be replaced. Do not attempt to open, clean, or repair the valve's internal mechanism.

No discharge at all when the lever is lifted usually means mineral deposits have seized the valve's internal mechanism shut, which is the more dangerous of the two failures, since a seized valve gives no protection at all if the tank ever does overheat or overpressurize. A valve that discharges but will not fully reseat is failing in the opposite direction: a worn seat or debris caught in the valve keeps it weeping continuously, which wastes water and, over time, can mineral-scale the valve itself into eventually seizing shut too.

Either failure has the same answer. A T&P valve is not a serviceable part with an internal repair kit; it is inexpensive, it is designed to be swapped as a whole unit, and a valve that fails a test should be replaced with a new one rather than left in place on the assumption that it might still work when it matters.

1. Turn off power to an electric tank at the breaker, or set a gas tank's control valve to pilot, and close the cold water supply valve.
2. Open a hot tap to relieve pressure, then drain a few gallons through the tank's drain valve to bring the water level below the T&P valve's port.
3. Disconnect the discharge pipe from the old valve, then use a pipe wrench to unthread the valve itself from the tank.
4. Apply pipe thread sealant rated for potable water to the new valve's threads and thread it into the tank's port, orienting the sensing probe so it extends into the tank as designed.
5. Reattach a discharge pipe, sized to match the valve's outlet, running it to within about six inches of the floor with no threads, no valve, and no upward run anywhere along its length.
6. Close the drain valve, refill the tank fully, purge air at a hot tap until the stream runs steady, and restore power or return the gas control valve to normal.
7. Test the new valve's lever once the tank is back up to temperature to confirm it discharges and reseats correctly.

Manufacturers commonly recommend testing every six months to a year, the same rhythm as checking smoke detector batteries, and for a similar reason: it is the only way to know a safety device still works before an emergency is the first time it is asked to. Lifting the test lever briefly does not meaningfully wear the valve; leaving it stuck open for an extended period, or testing it far more often than recommended, is unnecessary rather than harmful in moderation.

A valve that drips occasionally right after a test, for a few seconds as it reseats, is normal. A valve that continues a steady drip minutes later, or every time the tank runs a heating cycle with no test involved, is failing and should be replaced rather than watched.

A T&P valve that fails a test is swapped, not repaired. These are standard residential replacements to compare on outlet size and mounting orientation.