When a supply line lets go, minutes count, and most homeowners discover they do not know which valve to turn until water is already on the floor. A short walk through the house, done on a calm day, fixes that. The goal is simple: know where every shutoff is, what it controls, and whether it still works.
Start at the main shutoff
The main shutoff is the valve that stops water to the entire house. In many homes it sits where the line enters, often in a basement, utility room, crawl space, or along an exterior wall near the meter. Some homes also have a curb stop, a valve at the street or property line that is operated with a special key. Do not operate a curb stop yourself unless your utility or a licensed plumber has told you how. If you cannot find the main inside, ask a plumber to show it to you the next time one visits, and write down where it is.
Map the valves that serve each fixture
Next, walk every water-using area and note the local shutoffs. Under each sink there are usually two small valves, one for hot and one for cold, on the supply lines to the faucet. Toilets have a valve on the wall or floor behind the tank. Washing machines, dishwashers, refrigerators with ice makers, and water heaters usually have their own valves. Outdoor hose bibs and sprinkler lines often have separate shutoffs too. Write each one down as you find it, with the room and the fixture it serves.
Include the treatment equipment
If you have a softener, filter, or reverse osmosis unit, look for its inlet and outlet valves and any bypass valve. Confirm which valve isolates the unit and which one keeps water moving to the rest of the house. Ask the company that installed the equipment to show you these valves, and to explain which ones you should close for a repair and which ones should stay open. Keep that answer with your other notes so you do not have to reconstruct it under pressure.
Label and test each one
Tag each valve with a durable label or a piece of tape that names the fixture or area it serves. A label you can read from a standing position is more useful than a detailed one you have to crawl to see. Then test each valve once, gently. Turn it until it closes, then open it back up. A valve that moves smoothly and stops fully closed is doing its job. A valve that is stiff, will not fully close, or drips from the stem needs attention. Do not force a stubborn valve, because an old valve can break when turned hard. Call a licensed plumber to repair or replace it.
Keep the map where people can find it
Store your list with the other household papers, and put a copy somewhere easy to reach, such as a kitchen drawer or a note on your phone. Tell everyone who lives in the home where the main shutoff is and how to close it. The list only helps if the people in the house can use it on the worst day, so review it whenever you add a fixture, replace a valve, or change treatment equipment. For a broader look at how winning companies are selected if you are looking for help with this kind of work, see the award winners page.