Around the house · First steps · about 15 minutes

Shut Off Your Home's Water

When a pipe bursts or a sink overflows, every minute of running water adds to the damage. Your home has a main shutoff valve that stops water to the whole house, and most sinks and toilets have their own small valves. Find them now, before you need them.

When to teach it: Watch from about 6, help from about 9, do it alone from about 12.

A lever valve needs only a quarter turn. Find your main valve before you ever need it.

You'll need

Flashlight
A tag or tape and a marker, for labeling
A water key or wrench, only if your main valve needs one

Before you start

Learn where the main valve is now, before there's a leak.
Leave the valve at the water meter or property line alone. For that one, call your water utility or a licensed plumber.

Step by step

Tick each step as you go if you like; ticks stay on this device.

Look where the water comes inThe main valve is usually close to where the water line enters the house. In a basement, check the front wall facing the street, typically within 3 to 5 feet of where the pipe comes in. In a home without a basement, look near the water heater or under the kitchen sink. Some are on an outside wall or in an underground box.
Know your handleA round wheel handle closes by turning clockwise, and it may take two or more full turns. A lever handle closes with a quarter turn; it's off when the lever sits crossways to the pipe.
Close itTurn the handle to closed with steady pressure. If it's rusted, stuck, or won't close all the way, plan to have a licensed plumber repair or replace it.
Check that it worksOpen a faucet on the highest floor. This lets out the leftover pressure. The water should slow and stop. If it keeps flowing, the valve isn't closing fully.
Turn it back on slowlyOpen a wheel valve about half a turn, or a lever about halfway, so the pipes fill gently. Then open it all the way and let each faucet run until the sputtering air stops.
Find the fixture valvesLook under sinks and behind toilets for small valves on the water lines. A toilet's valve is usually on the wall behind it and closes clockwise. These let you shut off one fixture and keep water running everywhere else.
Label it and share itTag the main valve so it's easy to spot. Show everyone in the family where it is and how to turn it.

Physics

How it works: Water pressure and the one way in

The water in your pipes is under pressure. Pressure is a force spread over an area, measured in pounds per square inch (psi). Many homeowners set their house pressure to around 50 psi. A widely used plumbing code calls for a pressure regulator, a valve that lowers the pressure, when the supply pressure is over 80 psi.

Where does the push come from? Water systems use pumps, and water stored up high in tanks. Each foot of water height adds about 0.433 psi at the bottom. So if the water's surface sits 115 feet above your faucet, it pushes with about 115 × 0.433, which is close to 50 psi.

That pressure fills every pipe in your house at once. But all of it comes in through one service line, and the main valve sits on that line. Close it, and no new water can get in. Open a faucet to let out the leftover pressure, and the flow stops everywhere downstream.

pressure (psi) ≈ 0.433 × height of water (feet)

Try it: Use the formula: how tall would a water tower need to be to give 60 psi? (60 ÷ 0.433 ≈ 139 feet.) Next time you pass a water tower, guess how tall it is and estimate the pressure it makes.

Keep learning: Science

Teaching it to your kids

Go on a valve hunt together: the main valve first, then every sink and toilet.
Let your child practice closing and opening a fixture valve while you watch.
Play 'what would you do?': 'Water is spraying under the bathroom sink. What do you turn first?'

Tips

If a pipe breaks or bursts, close the main valve right away. The faster the water is off, the less damage it can do.
Check the main valve now and then to make sure it isn't rusty and still closes completely.
If your home has fire sprinklers, there may be two valves. Unless a sprinkler pipe is the one leaking, close only the household plumbing valve and leave the sprinkler pipes on.
Keep a flashlight near the main valve.

Common mistakes

Mistake	Instead
Hunting for the valve while water pours in.	Find it and tag it today.
Turning a lever handle around and around like a wheel.	A lever only needs a quarter turn. It's off when it points across the pipe.
Opening the main valve all the way at once after a repair.	Open it partway, let the pipes fill, then open it fully and let the air out of the faucets.
Using the valve at the meter or curb.	Use your home's own main valve. Call the water utility or a licensed plumber for the one at the meter.

Safe habits

Don't operate the valve at the meter or property line yourself. Call your water utility or a licensed plumber.

When to call a pro

If your home has no main valve, or it's rusted, stuck, or won't shut off completely, have a licensed plumber repair or replace it.
For the valve at the meter or property line, call your water utility or a licensed plumber.

Sources

Free how-to guides for families, with nothing to earn, pass or send in. They follow U.S. rules and sources; your owner's manual, product labels and state and local rules come first.