How to Fix a Leaking Water Heater

Updated: Apr. 01, 2020

Simple solutions for common water heater leaks.

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Fix common water heater leaks from a temperature and pressure relief valve or a water heater drain valve by checking temperature settings and mineral deposits. A simple cap solves the water heater drain valve problem.

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Diagnosing a temperature and pressure relief valve leak

The T & P valve, which stands for temperature and pressure relief valve, is a safety device that protects against excessive temperature and pressure levels in the leaking water heater. The valve is located on or near the top of the tank. Part of the valve extends into the unit.

If you have a water heater leaking from relief valve, it usually means the valve is defective (it opened and didn’t close) or the leaking water heater is operating under too high a temperature or pressure.

First, check the water temperature and make sure the setting is about 120 degrees F (or “medium” if your thermostat doesn’t have a degree reading). If you still see the pressure relief valve leaking, remove it and examine it for mineral buildup and signs of corrosion. The minerals in especially hard water can clog it or attack the metal parts, resulting in valve failure. This is especially common with water from a well. And if you have municipal water, check with your local water department to find out if the water supply has a high concentration of minerals. In either case, you’ll have to soften your water.

If the pressure relief valve looks clean, consider two other possible causes: high water pressure in the municipal system or some sort of backflow preventer around the water meter or main shutoff. You’ll need a licensed plumber to diagnose and handle these problems.

Stopping a leaking water heater drain valve leak

Stop a water heater drain valve leak

Screw on a hose endcap to stop the hot water heater leaking.

You’re supposed to flush your hot water heater regularly to remove sediment from the bottom of the tank. But many homeowners don’t do it until they hear rumbling from the tank. (Here are 21 things homeowners must know.) After the flush, they discover that the drain valve leaks. If the drain valve is brass, you can usually replace the washer. Repairing a water heater leaking from the drain valve is a fairly easy but time-consuming fix because you have to shut off the water and drain the tank. If you have a plastic drain valve, your best bet is to replace the entire valve. You guessed it; you’ll have to drain the tank for that fix, too. So how do you stop the drip until you get around to fixing the valve? Simple—buy a brass garden hose end cap and screw it onto the valve threads.

Required Tools for this hot water heater leaking project

Have the necessary tools for this how to fix hot water heater leaking DIY project lined up before you start—you’ll save time and frustration.

  • Adjustable wrench