The main water shutoff valve stops water to the whole house. Every home has one, and in an emergency it is the first thing to turn. Many homeowners do not know where theirs is until water is already on the floor.
This guide helps you find yours, test it and know what to do if it fails. Do it once on a calm day, and you will know what to do on a bad one.
Where to look
Near the water meter
In front of the house, in a ground-level box with a lid. The meter has a valve on the utility side and sometimes one on the house side.
On the house wall
Often at the front, on the side where the pipe enters the house, at about hose bib height.
In the garage
Look on the wall nearest the street, close to the water heater.
Inside a utility closet
Some homes have the valve inside, near the heater or a laundry area.
Follow the supply line. The pipe that enters your home from the street leads to the valve. If the water heater is in the garage, the cold supply near it is a good clue.
Two kinds of valves
| Valve | How it works | Notes |
|---|---|---|
| Gate valve | Round handle you turn many times | Older style, can seize or break |
| Ball valve | Lever that turns a quarter turn | Newer, reliable, easy to test |
| Meter valve | On the utility side of the meter | Belongs to the water district |
Do not force a stuck valve
A gate valve that will not turn can snap its stem. If it will not move with firm hand pressure, stop and call a plumber. Forcing it can turn a small problem into an unstoppable flood.
How to test your valve
Open a tap
Run a faucet at the lowest point in the house.
Close the valve
Turn clockwise or flip the lever across the pipe.
Watch the tap
The flow should stop in a few seconds. If water keeps running, the valve is not sealing.
Reopen slowly
Open the valve and let the pipes refill, then check for leaks.
Valve will not turn?
Call us to replace it before you need it.
When to replace the valve
A valve that is stiff, drips from the stem, leaves water running when closed or has a corroded body is due for replacement. A ball valve is a small part, and replacing an old gate valve is a quick job.
Replacing the main valve means shutting off water at the meter. For that, the water district's valve may be involved. We coordinate access with the utility when needed.
Other shutoffs worth knowing
- Under each sink and toilet, small angle stop valves.
- At the water heater, the cold water supply valve.
- At the washing machine, hot and cold valves.
- At the irrigation system, a separate shutoff.
Practice the shutoff as a household drill
Walk everyone who lives in the home to the main valve once and have each person turn it. It takes five minutes, and it turns an emergency into a routine task. A child or a guest should not be the only one who knows where it is.
Tie a tag to the valve with a label that says main water, and keep a small wrench or a valve key beside it if the valve needs one. A flashlight near it is a good idea too.
What to do after you shut the water off
Open a low tap
Drain the pipes so water stops flowing from the break.
Turn off the water heater
Switch off the gas or breaker so the tank does not heat without water.
Photograph the damage
Your insurer or landlord will ask for it.
Call a plumber
Tell us what you saw and where the water is coming from.
Do not turn the water back on until the plumber says it is safe. The pressure that returns can reopen a repair that has not set.
If you cannot find the valve at all
Some houses have been remodeled, and the valve is hidden behind a panel, a shrub or a stored item. Start at the meter and trace the pipe toward the house. Look in the garage, near the water heater and in any utility closet. Check for a small access door in a wall.
If you cannot find it, a plumber can locate it and, if needed, install a new accessible valve. It is a small job that can save a house.
Codes and licensing to know about
Plumbing in California is governed by the California Plumbing Code, which is based on the Uniform Plumbing Code (UPC). Whether a project like this needs a permit depends on the scope, so ask the City of Lemon Grove building department before you start. Contractors hold a C-36 plumbing license from the Contractors State License Board, which you can verify at cslb.ca.gov.
Plumbing in Lemon Grove: local notes
Helix Water District supplies Lemon Grove, and the water meter and the valve on the utility side of it generally belong to the district. Do not operate or repair a utility-side valve without talking to Helix first. The valve on the house side of the meter is yours.
If the meter box itself is leaking, call Helix, not a plumber. If water is spraying inside the house, close the house valve and call us.
Frequently asked questions
Clockwise for a round handle. A lever is closed when it crosses the pipe.
Twice a year keeps it from seizing.
It is possible, but the water must be shut off at the meter. Many people hire a plumber.
It stops water entering the heater. The tank may still empty if it is leaking.
Call Helix Water District. The meter and the utility side of the line are generally the district's responsibility. If the leak is on the house side, call us.