Water Heater Leaking: How to Shut It Off Fast

By Ray Bennett · Updated 2 October 2026 · 5 min read · Checked against the sources at the end

Water Heater Leaking: How to Shut It Off Fast

Short answer

Power or gas first, then the cold water going in, then open a hot tap upstairs. That order matters, because shutting the water off first on an electric tank can leave the elements running in a half empty tank, and Bradford White says a dry element gets hot enough to melt its copper in thirty to forty seconds. All three take about two minutes once you know where they are.

This page is for the two minutes after you walk into a room and find water on the floor. It is a procedure rather than a diagnosis, and the diagnosis can wait until it has stopped getting worse.

Three things, in one particular order. The order is not fussiness, it is the difference between a repair and a replacement.

Before you start

What to carry: a torch and towels. Two minutes, if you know where the valves are.

Gas or electric? It changes step one completely. A gas heater has a pipe running to it and a dial on the front. An electric one has a thick cable and a double breaker in the panel. Look before you reach.

Do this on a calm afternoon too. Find the breaker, the gas dial and the cold water valve now, and put a label on each. Nobody learns plumbing well at two in the morning with wet socks.

Two things that come before any valve. If you can smell gas, stop. Do not touch a switch, do not use a phone indoors, get everyone out and call the gas company from outside: why that smell means leaving.

If there is water anywhere near the electrics, kill the breaker before you stand in it. That means the water heater breaker, and if the water has spread, the main. Wet floors and a live cable are the one part of this that can hurt you.

The order, and why it is that order

Power or gas, then water, then pressure. Doing the middle one first is how people turn a leaking tank into a leaking tank with dead elements.

Check 1

Three moves, about two minutes

1. The power, or the gas. On an electric tank, find the breaker marked water heater, which is usually two switches joined together, and push it firmly off. On a gas tank, turn the control dial on the front from ON to OFF.

Why first: an electric element that is left switched on while the tank empties runs dry, and Bradford White says a dry element gets hot enough to melt its copper in thirty to forty seconds. A gas burner keeps firing at a tank that is losing water.

2. The cold water going in. There is a valve on the pipe entering the top of the tank, usually the one on the right. Shut it. That stops the tank refilling as fast as it empties.

3. A hot tap, upstairs if you have one. Open it and leave it. That releases the pressure in the tank, which slows whatever is coming out of the leak, and it lets air in so the tank can drain if you need it to.

That is the whole emergency. Everything after this can be done at your own pace.

Reading the valve

Two kinds of handle and one rule each. This is the bit people get wrong in a hurry.

Check 2

Make sure it is actually shut

A lever handle. Along the pipe means open. Across the pipe means shut. A quarter turn is the whole travel, so if you are still turning it after ninety degrees, you are forcing something.

A round handle. Clockwise to shut, gently, until it stops. Do not crank it hard at the end.

If it will not move at all. Old valves seize. Do not break it. Go to the main stop for the whole house instead, which is usually where the supply enters, near the meter, in a basement, a garage or a utility cupboard, and sometimes in a small covered hole outside by the boundary.

If it turns but water keeps coming, the valve is passing and the house stop is the answer again.

Check it worked. Open a hot tap and watch it die away to nothing over a minute or two. If it keeps running strongly, something is still feeding the tank.

Draining it, if you need to

Check 3

Only once the power and water are off

Sometimes shutting it off is enough and you wait for a plumber. Sometimes you want the forty gallons out of the room.

Attach a hose to the drain valve at the bottom, and run it to a floor drain, outside, or into buckets if there is nowhere lower. The tank drains by gravity, so the end of the hose has to be below the valve.

Leave a hot tap open. Without air coming in, it drains very slowly or not at all.

The water is scalding. A tank that was working an hour ago is full of water at 120 degrees or more. Either wait for it to cool or treat every drop as dangerous.

Do not use the pressure relief valve to drain it. It is a safety device, they do not always reseat once opened, and you can turn one problem into two: what that valve is for.

Do not switch it back on until it is full. On an electric tank, power to a partly empty tank kills the elements immediately.

Then work out where it came from

Once it is off and stable, the question is whether this is a plumbing repair or a new tank, and that depends entirely on where the water was coming from.

Water from a fitting at the top, or from the drain valve at the bottom, is usually a repair. Water appearing from underneath the jacket itself is usually the tank, and a tank that has rusted through is not repairable.

The trail starts here: how to find where it is actually coming from. If it turned out to be the little valve at the bottom, that one is a cheap fix: the drain valve.

Questions people ask

Can I just turn the water off at the main and leave it?

You can, and it works, but it also leaves the whole house without water. Shutting the tank’s own valve does the same job and lets everybody carry on.

Should the gas dial go to OFF or to PILOT?

OFF for a leak. PILOT is for going away for a weekend. If the tank is emptying you want nothing burning under it at all.

How do I know which breaker it is?

Look for a double width switch, usually 25 or 30 amp going by Whirlpool’s sizing table, often labelled. If nothing is labelled, switch the main off. Guessing wastes time you do not have.

There is no valve on the pipe into the tank.

That happens on older installs and it is worth fixing afterwards. For now it is the house stop, and add fitting a proper isolating valve to the plumber’s list.

It stopped on its own. Do I still need to do this?

A leak that stops usually means the tank cooled and the metal moved. It comes back, and it comes back bigger. Treat a leak that stopped as a leak.

Can I keep using it until somebody comes?

Not if water is coming from the tank itself. Every hour it runs is more water and more heat behind a failing wall of steel.

Sources: Rheem use and care manual AP23698 (gas off at the control first, then the cold water supply, then a hot faucet to admit air, garden hose to a drain, water hot enough to scald, smell of gas), Whirlpool Energy Smart use and care guide 318686-001 (power off, cold water inlet valve, hot faucet, no power until the tank is full, branch circuit sizing guide), Bradford White "Draining a Water Heater" and "Heating Elements" on For The Pro (dry fired elements, thirty to forty seconds)