how to fix a leaky water valve

Pressure relief valve on hot water heater. — The pressure relief valve on a hot water heater can leak over time.

I just flushed my hot water heater as you mentioned and now the pressure relief valve is leaking. Is this something I can replace on my own, or should I call a plumber? —Leighton

Hi Leighton,

Pressure relief valves sometime develop a drip when opened for the first time in years. Try opening and closing it a few times to see if it will seat itself. If you have a large leak or the drip doesn't stop on its own in a day or two, the valve will need to be replaced. Whether you can replace it yourself will depend on your skill level, but as far as plumbing repairs go, it's not that difficult. If you do try to fix it, here are the basic steps involved:

First, turn off the gas to the water heater, or flip the breaker if it's electric.
Close the cold water cut-off valve going into the water heater.
Open the valve at the bottom and the pressure relief valve for a minute to drain a little water out of the tank and relieve the pressure.
Remove the overflow pipe from the pressure relief valve. If it's been glued or soldered in place, it may have to be cut off.
Use a pipe wrench to unscrew the old pressure relief valve.
Wrap Teflon tape around the threads of the new valve, and screw it in until tight, orienting the overflow pipe opening away from the tank.
Reattach the relief valve drain pipe using Teflon tape on the threads. If you have to replace the drain pipe, use pipe (and glue) that is rated for hot water (such as CPVC rather than PVC).
Open the cold water cut-off and check for leaks around the relief valve.

Good luck with your project,

Danny

Further Information:

Water Heater Maintenance (video)
Closing Pressure Relief Valve When Draining Hot Water Tank (article)