When a pipe bursts or a supply line lets go, every minute of running water adds to the mess. The main water shutoff stops water to the whole house, and the time to find it is on a calm afternoon, not with water on the floor.
Where to look
The main shutoff is usually close to where the water line comes into the house. Common spots:
- On a basement or crawlspace wall, often the side facing the street
- Near the water meter, if your meter is inside
- In a utility room or near the water heater
- In the garage
- Outside near the foundation or in a covered box, in some warmer areas
- Near the pressure tank, if your house is on a well
There's often another valve at the meter box near the street. That one usually belongs to the water utility and may need a special key, so check with your water provider before you use it.
The two common valve types
A round wheel handle (often a gate valve) turns clockwise to close and takes several turns. A lever handle (a ball valve) is a quarter turn: when the lever sits across the pipe, it's closed; when it lines up with the pipe, it's open.
Test it gently
Turn the valve off, open a faucet to make sure the water stops, then turn the valve back on slowly and close the faucet. If the valve won't budge, don't put a big wrench on it. Older valves can break, and then you have a bigger problem. If it's stuck, drips at the handle, or won't shut the water all the way off, have a licensed plumber replace it. That's a job worth doing before an emergency.
Know the smaller shutoffs, too
Most leaks start at one fixture, and those usually have their own valves: under the kitchen and bathroom sinks, behind each toilet, on the cold-water line at the water heater, and behind the washing machine. Turning off just that valve stops the leak without shutting down the whole house.
Make it easy for everyone
Keep the path to the main shutoff clear. Put a tag on it. Show everyone who lives in the house, and anyone who watches the place when you're away. Write down where every valve is, so nobody has to remember it under pressure.
If there's a leak right now
Shut off the main first, then call a plumber. If water is near outlets, cords, or your electrical panel, stay out of it and call a pro. And if you ever smell gas, leave the house and call your gas utility or 911 from outside.
Put it on paper
The Shutoff Valve House Map gives you a simple page to walk the house once and mark every shutoff, and the Shutoff Valve Tags make the valves easy to spot when it counts.
From the shop
General homeowner info, not a substitute for a licensed plumber. Gas, electrical, and anything beyond basic work are jobs for a licensed pro.