There is one basic prerequisite for most plumbing projects: Shut off the water to the work area, then test to make sure the water supply is shut off. Failing to shut off the water can lead to a mess, with water spraying all over the place, and possible damage to flooring.
Every adult family member should know how to shut off the water, both at the fixtures and to the entire house. Find tips and information on stop valves for the kitchen sink, saddle tee-valves, in-faucet stop valves, the main shutoff for the entire house, intermediate shutoff valves, buffalo boxes, water meters, and more below.
Most homes built in the past 40 years have a separate stop valve (also called a fixture shutoff valve) for each faucet, toilet, and fixture. A supply tube (sometimes called a riser) runs from the stop valve to the fixture. (A faucet has two stop valves, one for hot water and one for cold; a toilet needs only a cold-water shutoff.) If a fixture does not have a stop valve, you will have to shut off water to part or all of the house before working. It's a good idea to install a stop valve so you can stop the flow quickly in case of emergency.
A stop valve typically has a body with a chrome finish and an oval handle. In an older home it may be shaped like a hose valve with a round or decorative ceramic handle.
Most stop valves are made for light duty because they are used only for emergencies or repairs. That means they might not shut off the water completely. Do not crank down on its handle with pliers; you may break the valve. Some close in only a quarter turn.
Every home has at least one main shutoff, which controls water flowing to the entire house. Often there is one main shutoff inside the house and another outside.
An inside main shutoff is usually located near the point where water enters the house. Often it is near the water meter. There may be two valves, one on each side of the meter. If your home has no meter (some homes don't), look for a large pipe that enters the house, often through a basement floor or at the bottom of a crawlspace. The shutoff should be somewhere along the run of that pipe.
In regions where winters are mild, the main shutoff valve may be outside the house.
An outside shutoff valve is near the point where a pipe branches off from the utility's main line to bring water to your home. If you have a parkway—a narrow strip of land between the sidewalk and the street—the outside shutoff will likely be there. If you cannot find yours, ask your water utility department where to find it.
In temperate regions an outside shutoff is usually housed in a plastic or concrete underground container, sometimes called a Buffalo box. Usually the box lid can be pried up, but you may need to dig away vegetation to free it.
In colder regions the shutoff will be below the frost line, typically at the bottom of a tube covered with a cast-iron cover. You may need a key, a long-handle wrench, to be able to reach down to the valve and turn the water on and off. Keys are usually the same size and type throughout a neighborhood. Often your water utility department will loan you a key for your shutoff.
You may find other shutoff valves on exposed supply pipes in a basement, crawlspace, utility room, or access panel behind a bathtub. These will probably be in pairs, one for hot and one for cold water. (If the water has been running recently, you can tell which pipe is hot by feeling them with your hand.) These are probably intermediate shutoffs, meaning they control water supply to a portion of a house.
To find out what a shutoff valve controls, close it and go through the house turning on faucets and flushing toilets. Remember that a toilet with a tank will flush once after the water is off; listen or look for water refilling the tank after the flush.
If you have hot-water heat in your home, there will be shutoff valves near the boiler. These have nothing to do with the supply pipes for your plumbing fixtures.
To keep track of water usage or to check that the utility is charging correctly, read your water meter. If your meter has a series of dials, each is labeled for the number of cubic feet it measures. It may be that some dials turn counterclockwise while others turn clockwise. A meter with a digital readout simply displays the amount of cubic feet of water used. Note the number at the start of the month or billing period, then read it again at the end and subtract the first number to calculate your use.
Kitchen sink stop valves, which allow you to shut off water to the faucet, often are hidden amid pipes and tubes under the sink. There may be a separate stop valve for the dishwasher.
A saddle tee-valve tied into a supply pipe runs cold water to a refrigerator's icemaker. Although a saddle tee is a handy way to tap into a line, some municipalities forbid its use. Check local building codes.
In-faucet stop valves are found on some tub/shower faucets. Use a large slot screwdriver to turn water on and off.
An in-house main shutoff, a fairly large valve found near the point where water enters the house, shuts off water for the entire house. As shown above, the shutoff valve is often next to the water meter.
A Buffalo box is another type of whole-house shutoff. Common in the South and Southwest, this box is buried outdoors. Pry off the lid. Inside you'll find a standard valve that you can turn with your hands or one that requires a special key.
Intermediate shutoff valves control water flow to part of the house. There will be two or more pairs of these.