Plumbing tips · October 29, 2026
The water heater pipe that weeps
The pipe running down the side of a water heater is there on purpose. When water comes out of it, something is telling you the tank is too hot, too pressured, or the valve itself is worn.
What the valve does
Every tank water heater has a temperature and pressure relief valve, usually near the top with a pipe running down toward the floor. If the water gets too hot or the pressure too high, it opens and lets water out so the tank does not.
Never cap or plug it
A dripping relief valve is annoying, but it is the one part keeping the tank safe. Capping the pipe, plugging it or tying the lever shut takes that protection away. Put a bucket under it and have it checked.
Why it drips
The valve itself can wear out or get grit in the seat, so it never closes all the way. The thermostat can be set or stuck too hot. Or the water pressure in the house is too high, often because the pressure reducing valve has failed or there is no expansion tank.
What to check
Feel whether the water coming out is very hot, and notice whether it drips after someone runs hot water or all the time. A plumber can test the house water pressure with a gauge and tell whether the valve, the thermostat or the pressure is to blame.
Questions we get asked
Why does it drip at night but not during the day?
City water pressure often climbs at night, when hardly anyone in the neighborhood is using water. A valve that only drips then points to high house pressure rather than a hot thermostat.Can I just replace the relief valve myself?
It has to be the right rating for that heater and installed with the water off and the tank drained down. And if the cause is high pressure, a new valve will start dripping again.What is an expansion tank for?
Water expands when it heats. On a house with a check valve or pressure reducing valve, that expansion has nowhere to go, and the pressure climbs until the relief valve opens. An expansion tank gives it room.Plumbing questions we answer
Where we go
Parker, Wise and Tarrant County, out of the shop in Springtown. Springtown, Weatherford, Azle, Boyd, Decatur, Newark, Millsap, Fort Worth and the country in between.
Call 817-487-8866