What is a shutoff valve?
A shutoff valve is a mechanical device that stops the flow of water to a home or specific fixture when turned off, typically located where the main water line enters the property or near individual fixtures like toilets and sinks.
A shutoff valve controls the flow of water to your home or to individual fixtures like toilets, sinks, and washing machines. The main shutoff valve sits where the water service line enters your property, usually in the basement, crawl space, or under the kitchen sink. Individual fixture shutoff valves are installed behind or under sinks, toilets, and other water-using appliances.
Knowing where your main shutoff valve is located matters for emergencies. If a pipe bursts, a fixture leaks, or water damage threatens your home, you need to locate and turn off water quickly to prevent further damage. Waiting for a plumber to find it can mean thousands of dollars in water damage. Similarly, shutoff valves on individual fixtures let you repair or replace a toilet or faucet without turning off water to your entire house.
Shutoff valves typically use a lever handle or a round handle that you turn clockwise to stop water flow. Over time, valves can become stuck or corroded, especially if rarely used. A licensed residential plumber can locate your main shutoff, test it to ensure it works, and install or repair fixture shutoff valves as needed.