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How to Shut Off Your Water Supply and Stop a Leak

Water leaking under a sink

Water leaks are never fun. When you detect a leak, the first thing you need to do is locate it and then shut the water off.  Here’s how.

There are a few places where you can shut off the flow of water, starting from the malfunctioning fixture and working your way backward. Appliances and fixtures have shutoff valves, and your whole house has a shutoff valve. The key is to work backward starting with the shutoff points closest to the leak (there’s no reason to kill the flow of water to your dishwasher and water heater if the leak is the toilet tank in the bathroom, after all).

For example, let’s say your kitchen faucet is leaking. If shutting off the faucet doesn’t work, go back to the shutoff valve under the sink. If that doesn’t work, head down to the basement and see if there is a shutoff valve under the kitchen. If that doesn’t work, you can head to the whole house valve. Let’s take a look at the different kinds of valves you’ll encounter.

Before we jump in though, a bit of advice. The best time to learn where all the valves in your house are is before you’re rushing around with a bucket and a mop dealing with a leak. If you have the good luck to be reading this article at a time when water isn’t spraying all over your bathroom, we’d recommend reading through it and then walking through your house looking at all the places there is water access—the kitchen, the bathroom, the utility room, etc. As you do, ask yourself “Where is the valve for this?”

It’s way more fun to find the valves when you’re not panicking as water flows across the bathroom floor. Trust us.

The Valves, Big and Small

Under sink service valve
A typical under-sink service valve. Adam Doud

There are several different kinds of valves you may encounter. Most indoor fixtures and appliances have shut off valves before the pipe goes into the wall. The main exception to this rule is the bathtub, which we’ll talk about later.

Typically the valves for sinks and other bathroom and kitchen fixtures will have a football-shaped knob—like the one in the photo above—that you turn clockwise to close. Appliances such as a water heater or dishwasher will typically have a ball valve which is a handle that is turned from perpendicular to the pipe (closed) to parallel with the pipe (open).

Appliances with smaller water demands, like the water dispenser and ice maker in your fridge or a whole-house humidifier attached to your furnace, will often be connected to an existing water line by a saddle valve—a small add-on water valve that is screwed into the wall of an existing pipe and connected to the appliance by a small copper or flexible tube. Saddle valves are closed the same way, by turning the handle clockwise, but be careful when twisting them as they are much more prone to snapping than their larger counterparts.

Outdoor fixtures typically have circular knobs, like the kind you usually find on an outdoor spigot and it’s not uncommon to find a matching knob on the inside of the house to turn off the water for winterization.

Finally, depending on the age of your home and whether or not the plumbing has been updated over the years, the main service line coming in from the street could have a ball valve or a circular spigot-style valve.

Fortunately, in most cases, turning water on or off doesn’t require any tools. However, in some cases, you may need a crescent wrench, or basin wrench to get at the shutoff valves. This is usually only the case for the main water supply discussed later. You might want to have a can of WD-40 or another penetrating agent on hand in case the valves don’t turn freely.

Work Backwards from Leak to the Nearest Valve

Hand turning a plumbing ball valve

Now that we know what kind of valves we’ll encounter, we’re going to work backward. Water fixtures and appliances in your house will have shutoff valves in case something goes wrong, or you need to upgrade or replace them.

Different appliances will have valves in different locations. Faucets will generally have two shutoff valves – one for hot water, one for cold – underneath the sink. Toilets will have a single shutoff valve right below the tank. Dishwashers, washing machines, and other appliances will have a single shutoff valve near the floor (or, potentially, beneath the floor in the basement). Water heaters, depending on the type will have a shutoff valve before the intake.

Bathtubs can get complicated because their shut off valves are harder to find. Look for an access panel somewhere around the side or back of the tub. Sometimes, the entire front panel of the bathtub comes off, and you’ll find the shutoff valve in there. Other times, the bathtub backs up to an exposed crawl space, and you’ll find the shut off there.

Plumbers often have to be creative when it comes to placing the shutoff valve for a bathtub. Sometimes, it’s a removable panel in the next room or a closet. If your home has a “plumbing wall” you might find the shut off for the upstairs bathroom in the basement. It’s no accident that bathrooms tend to be stacked on top of each other.

In any case, locate the valve for the appliance or fixture that you want to replace and turn it clockwise, or turn the lever so that it runs perpendicular to the pipe.

When In Doubt, Throw the Main Valve

The main shut off valve is located next to the water meter
Adam Doud

In the event you need to turn off the water to your entire house, you can use the main water valve on the house side of your water meter. Your water meter is often located outside of your home in a cement box buried in the ground. It can also sometimes be found in the house. In some cases, the main water shutoff can be found in a basement or crawlspace. The main shut off valve will always have a water meter with it.

Once you locate that, you’ve located your main shutoff valve. Often, it’ll look like an outside fixture valve or a ball valve—just turn the circular valve clockwise or turn the ball valve handle perpendicular to the pipe.

Water’s Off. Now What?

If you needed to turn the whole house off to stop your leak, you might need to drain the system, especially if the leak is on the first floor or basement. Start in the upper levels of your house and turn on all your faucets and fixtures. Once drained, work your way down. This process releases the water pressure from the system. If you don’t do this, then your leak will continue to leak until the system is completely depressurized. Depending on the size of the leak this could take a very long time and be quite a hassle to deal with. Depressurizing the system and releasing the water ensures the leak stops faster.

While you’re draining the system, be sure to turn off your water heater. Electric heaters are simple to turn off and back on, but if you have an older gas water heater and aren’t familiar with how it works, please contact your utility company or knowledgeable contractor or friend to help. Typically for a gas heater you don’t turn it completely off, but simply dial it back to the pilot light setting. You should only need to cut the gas to the water heater entirely if you’re draining the water heater itself as part of your leak repair.

Turning the Water Back On

Water flowing from a kitchen sink faucet

Of course, once you’re done with your project, you can turn the water back on. If you turned off the water in the whole house, you’ll need to go through the house and bleed off the air by slowly opening the hot and cold faucets throughout your home one by one. Expect a lot of noise, sputtering, and a bit of splashing as the pipes are purged of air and returned to normal operating conditions.

Also, you may find water pressure diminished in some fixtures after turning the water back on. This is often due to sediment that has shaken loose and is now trapped in the water fixture. Most water fixtures have a screen, aerator, or cartridge that has become clogged with sediment. Remove the screen and clear the blockage and you should find water pressure returned to normal levels.

Finally, double check your water heater to ensure it is operating correctly—especially if you have a gas water heater. Again, if you have any doubt that your gas heater is functioning correctly contact your utility company or a knowledgable friend to confirm.

Adam Doud
Adam is a full time writer/blogger/videographer/podcaster. By day he hosts the podcast and the podcast. By night, he creates content for multiple sites including Android Authority, DGiT, LifeSavvy, Booredatwork, Reviewed, and more. Read Full Bio »
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