How to Find and Test Your Main Water Shutoff Before You Need It

The shutoff that ends a flood is the one you can find and close in under a minute. Plenty of people discover during a burst pipe that they have never located it, or that it has not moved in twenty years and will not turn. IBHS’s guidance on preventing interior water damage tells homeowners to know the location of the main shutoff and to turn it off when traveling. Triple-I’s winter guidance says the same thing in different words: know where your pipes are and learn how to shut the water off. This post is the practical version.

Two valves, two owners

On a typical single-family lot there are two places the water can be stopped on the supply line, and they are not equivalent.

• The meter valve. In a box at the edge of the property, near the street. It belongs to the water utility. Many utilities treat it as theirs, and the lid may need a special key. Ask your utility whether residents may use it.
• Your main shutoff. On the line where it enters the house, usually inside a garage, utility room or closet, or outside against an exterior wall. This is the one meant for you.

Below those are the smaller valves: one on the water heater, a stop valve under each sink and behind each toilet, one at each washing machine hookup, and one at each outdoor faucet. These stop a single fixture, which is useful for a leaking toilet supply but does nothing for a burst line in a wall.

How to find your main

1. Find where the water enters. Walk to the side of the house facing the street. The line from the meter comes in near the same spot, often at an exterior hose bib, a utility closet or the garage wall.
2. Look at the water heater. The cold supply line feeding it often has a valve, and the main is frequently within a few feet of it in houses where the heater is near the entry point.
3. Follow the meter. The line from the meter box to the house shows where the main must be, even if it is hidden behind a panel.
4. Check the plans or ask. If the house has a plumbing diagram, a home inspection report or a seller’s disclosure, it may say. A plumber can find and label it in a few minutes.
5. Mark it. A bright tag, a photo on your phone and a note in the household’s emergency list is enough.

Ball valves and gate valves

The twice-a-year test

1. Tell the household. Water will be off for a few minutes.
2. Close the valve slowly. For a ball valve, a quarter turn. For a gate valve, turn the wheel clockwise until it stops. Do not force it past firm resistance.
3. Check that it worked. Open a faucet on the lowest floor. Water should stop within a few seconds.
4. Look at the valve. Any drip at the stem or the connections is a sign it needs service.
5. Reopen it slowly, then open a faucet for a moment to clear air from the lines.

While you are there, you can run a leak check. EPA’s WaterSense program says to check your water meter before and after a two-hour period when no water is being used, and that if the meter changes at all, you probably have a leak. The shutoff is the other half of that test: with the valve closed, a meter that still moves means the leak or the meter itself is on the street side of the valve. The hidden leak guide covers the rest.

If it will not close or leaks

• In an emergency, call your water utility’s emergency line and tell them water is running inside a building. They may be able to close the supply at the meter.
• Close the valve at the water heater and at the affected fixture if the leak is limited to one place.
• After the emergency, have a licensed plumber replace the valve. A ball valve is a modest, common repair, and having one is worth it.

Fixture shutoffs and when to use them

The main closes the whole house. The small valves close one fixture, and they are the right tool for the most common household leaks, which come from a toilet supply, a faucet connection or an appliance hose.

A valve that has not moved in years is a risk of its own. If a stop leaks when you turn it or will not close, have a plumber replace it while nothing is wrong. Leak sensors and automatic shutoff valves exist as add-ons and shorten the time a leak runs, but they do not replace knowing where the manual valves are.

Condos, apartments and shared buildings

In a multi-unit building there are usually two layers. Your unit may have its own shutoff under a sink, in a utility closet or near the water heater, and the building has risers and branch valves that only management or the building engineer can close. Find your unit shutoff now. Ask management where the building valves are and who to call after hours, and put that number in your phone. In a leak that starts in another unit, you may not be able to stop it yourself at all, which is why the first call is to management.

A 60-second drill for the household

Knowing where the valve is does not help if only one person knows. Once a year, walk everyone who lives in the house to the valve, say what it does and have each adult close and reopen it. Take a photograph of the valve and put it with your emergency contacts. Tell guests and house sitters before they stay.

Before you travel

IBHS’s recommendation is to turn the main off when traveling. For a house that will be empty for more than a few days, especially in winter, that single step removes the biggest risk: a supply failure that runs unnoticed. If you leave the water on for a reason, such as an irrigation system or a pet, have someone check the house on a schedule. The vacant house winter checklist goes through the rest of the list.

Read about frozen and burst pipe cleanup →

This article is general information from the Dallas Flood Guard editorial team. It is not medical, legal, engineering or insurance advice. Sources are linked above. See the editorial policy for how posts are researched and corrected.