How to Shut Off Your Water Main in an Emergency
Your main water shutoff is usually a valve where the water line enters the house, in the garage near the water heater, on an exterior wall by a hose bib, or in the crawlspace. Turn it clockwise until it stops, then open a low faucet to drain the lines. If you cannot find it, use the customer valve in the meter box at the street. CNTRline answers 7 days a week at (707) 308-5599.
Step by step
- Find the house side shutoff valveLook where the main water line enters the house. In Sonoma and Marin homes the usual spots are the garage wall near the water heater, an exterior wall next to a front hose bib, or the crawlspace near the foundation. You are looking for a wheel style gate valve or a lever style ball valve on a 3/4 inch to 1 inch pipe. Find it on a calm day and tag it so anyone in the house can find it fast.
- Turn the valve clockwise until it stopsA gate valve wheel takes several full turns clockwise to close. A ball valve lever takes a quarter turn, so the handle ends up across the pipe instead of along it. Turn firmly but do not muscle a stuck valve with a wrench. Old gate valve stems snap off, and then the leak has company.
- No house valve? Use the meter box at the streetFind the concrete or plastic meter box at the curb, usually in line with the front hose bib. Pry the lid with a screwdriver. The valve on the house side of the meter is yours to close, and a cheap meter key from the hardware store makes it easier. The valve on the street side of the meter belongs to the water utility. Leave that one alone. If you need the utility side shut, call your provider, such as Marin Water or your city water department, and they will send someone.
- Open a low faucet to drain the pressureWith the main closed, open the lowest faucet in the house, a tub spout or an outside spigot, and crack one upstairs faucet to let air in. The pipes drain down and pressure falls, which slows the leak to a dribble and then stops it. Expect a minute or two of flow.
- Shut off the water heater if the water stays offIf the house will sit without water for more than an hour, or the leak is at the water heater itself, shut the heater down too. Gas unit: turn the control dial to OFF. Electric unit: flip the water heater breaker in the panel. A heater that fires on a partly drained tank can wreck the tank or burn out elements.
- Contain the damage and call for the repairMop standing water, move belongings clear, and get air moving across wet spots. Photograph everything before cleanup for insurance. Do not turn the main back on until the failed pipe or fixture is fixed or isolated. CNTRline answers 7 days a week at (707) 308-5599, and we will talk you through the shutoff on the phone while a plumber heads your way.
Frequently asked questions
Look under the home near where the supply line comes up through the floor, usually behind a skirting access panel on the same side as the water heater or bathrooms. Many parks also have a valve at the pad, next to the water spigot or utility pedestal. Ask the park manager where yours is before you need it, and ask who owns the pad valve.
Do not force it with a pipe wrench. Old brass gate valve stems shear off and the packing can start leaking, which adds a second failure to the first. Close the customer valve at the meter box instead. Then have the dead valve replaced with a quarter turn ball valve. It is a quick job and the best cheap upgrade an older house can get.
Usually, yes. Toilets and sinks have small angle stop valves on the supply lines under or behind the fixture. Turn them clockwise. Washing machines have lever valves at the wall box. The water heater has a cold water valve on the inlet at the top. If the fixture valve is missing or will not close, go to the main.
Yes, if the leak is at the heater or the water will stay off more than about an hour. Gas: turn the dial to OFF. Electric: flip the breaker. Electric elements burn out in minutes without water around them. When water is back, let the tank refill and run a hot tap until the sputtering stops before you relight or power up.
Free Homeowner's Guide
The Sonoma & Marin Homeowner’s Plumbing Guide
Spot problems before they flood, find your shutoffs, and see real 2026 cost ranges. A free PDF, straight from a licensed local plumber.
- 5 signs to call before it floods
- Where your three shutoffs are
- Real 2026 cost ranges for the big jobs