Hot Water Heater Leaking? Here's What to Do

First Steps if Your Water Heater is Leaking

Check whether it’s a leak or condensation. It’s normal for condensation to form on the outside of a water heater. If you only see a little water, watch to see if it eventually evaporates. If it does, it’s probably condensation. If the water pools without evaporating, it’s likely a leak. You can also wipe away the water and watch to see how it returns. If moisture forms uniformly over the side of the tank, it’s condensation. If the water comes back in drips or rivets, it could be a leak.

Turn off the power or gas to prevent fire. If you have an electric water heater, turn off the power at the breaker. If you have a gas heater, turn off the gas valve on the gas line. You can also turn off the gas at the gas control on the water heater itself.

Turn off the water if the leak is severe. If water is pouring or spraying out of the water heater, turn off the water supply to prevent flooding. But if the water seems to be leaking slowly, leave the water on—it may make it easier to find the source of the leak. The water shut-off is typically attached to the cold water intake near the top of the tank. If you can’t find it, check the owner’s manual for your specific heater.

Open a valve or tap to depressurize the heater. Pressure can build up inside your hot water heater, which can be dangerous when you’re working on it. To release some of that pressure, either lift the lever on the temperature and pressure (T&P) valve and let a little water drip out, or turn on a hot water tap inside your home for a few seconds. If you open the T&P valve, put a bucket under it to catch any water that comes out.

Find where the water is coming from. Try to determine the general location of the leak—is it coming from on top of the water heater, somewhere along the side, or on the bottom of the tank? Try these tips to determine where the leak is located: Look for areas where the leak may have caused rust or corrosion to appear on the tank. Check the valves, connections, and fittings to see if they’re leaking. Dry the water, then watch to see where new water comes from. Laying down paper towels can help you see where the moisture first appears.

What to Do If Water is Leaking from the Top of the Tank

Check the pipes leading to the water heater. The cold water intake and hot water output pipes can sometimes become loose, allowing water to leak out. Feel around these pipes and their fittings to see if that’s where the water is coming from. If that’s the source of the leak, use a wrench to securely tighten the connectors holding the pipes in place.

Feel for leaks coming around the top seam. Carefully run your fingers all around the seam where the top of the tank meets the body. If the seam is leaking, you’ll probably need to replace the tank. Double-check to be sure that's the source of the leak. Water coming from the fittings may gather along the seam, making it seem like that's where it's coming from.

What to Do If Water is Leaking from the Side of the Tank

Check for leaks around the T&P valve. The temperature and pressure (T&P) relief valve releases pressure that builds up in the tank. Check the threaded connections around the valve, as well as the bottom of the pipe leading from the valve. Leaks from the T&P valve could mean: The water temperature is set too high, so too much pressure is building up inside the heater. Use a flathead screwdriver to turn the temperature down to 120–125 °F (49–52 °C) to fix the problem. The water pressure is too high. Check that the pressure-reducing valve is set to 50-60 psi. You may need to install an expansion tank onto your cold water inlet pipe to prevent excess pressure from building up inside your main tank. The valve is damaged or faulty and needs to be replaced.

Open the T&P valve to make sure it’s working. Place a bucket under the T&P discharge pipe, then lift up the lever on the valve. Once you see a little water coming out of the pipe, let go of the lever so it snaps back down. If no water comes out when you lift the lever, or if water keeps coming out after the lever snaps back down, replace the T&P valve.

Check the heating element or gas control. If you have an electric water heater, check whether water is leaking from the heating element gaskets. You may need to replace these gaskets. If you have a gas water heater, check the gaskets around the gas control near the bottom of the tank. Replace these gaskets if they’re leaking.

What to Do If Water is Leaking from the Bottom of the Tank

Check the drain valve for leaks. Feel around the drain valve to see if water is coming out from around it. If it is, try tightening the drain with a flathead screwdriver to see if that stops the leak. If closing the drain valve doesn’t stop the leak, you may need to replace the valve.

Look for cracks or corrosion on the body of the tank. If the tank is damaged by corrosion, you might notice rust on the outside of the water heater tank or rusty water coming out of your taps when you turn on the hot water. If the tank is cracked, you might feel water coming out from around the bottom seam of the tank. If your tank is cracked or corroded, you’ll need to replace the whole water heater.

Is a leaking water heater dangerous?

Yes, a leaking water heater can be dangerous. Any time water leaks near electricity, it can pose a fire hazard. Also, leaking water can lead to mold growth. Call a plumber if you can’t find or repair the source of the leak.

How to Prevent Water Heater Leaks

Inspect your tank regularly to help prevent leaks. Every few months, visually inspect your water heater to ensure it’s in good working condition. Check the valves, drains, and connections to ensure they’re free of rust or wear and tear. Open the T&P valve once a year to test it. Not only will this ensure it’s working properly, but flushing the T&P valve regularly can help prevent mineral buildup from blocking the valve and causing leaks.

Flush the tank once a year to prevent leaks due to sediment buildup. To drain the tank, home improvement specialist Patrick Johns recommends turning off the power or gas to the water heater first. Then, turn off the water and attach a garden hose to the drain valve, then take the other end of the hose outside. Open the valve and let the tank empty completely. When you’re finished, close the valve and refill the tank, then turn on the power or gas and the water. Over time, sediment and minerals can build up inside your water tank. This can cause your water heater to work less efficiently. It can also cause the valves to stick, leading to leaks.

Replace the anode rod every 3–5 years to prevent corrosion. To check your anode rod, turn off the power or gas to the tank, then turn off the water. Open the drain valve and empty a few gallons of water into a large bucket, then find the anode rod near the top of the tank. If the anode rod has corroded to less than ⁄2 in (1.3 cm) or if it’s covered in calcium deposits, replace it with a new one. To replace the anode rod, use a socket wrench to release the old one. Wrap PTFE tape around the threads of the new rod to secure it, then screw it tightly into place. Then, refill the tank and turn the gas or power back on.