When a pipe lets go, the clock is running. Every minute it stays on is another minute soaking into floors and walls. Turning it off is easy. Finding the valve eats the minutes, so walk it once on a calm evening.
The steps below follow Any Hour Services from the meter box at the curb to the main valve inside. The rest is here: the b-box at the meter, and what to do when the valve will not budge.
What you need
- A flashlight - the valve lives in the darkest corner
- A water meter key, or a long flathead screwdriver, for the meter lid
- A curb key (also sold as a b-box key) for the meter-side valve
- An adjustable wrench or tongue-and-groove pliers for a stiff handle
Where the main shut-off valve actually is
The line runs from the city main past the meter near the street and takes a straight shot into the house. The main shut-off sits just inside, where it crosses the foundation.
- Basement or crawlspace: on the entry wall, near the water heater and pressure regulator.
- Slab house: the garage wall closest to the street, a utility closet, or a lidded box outside.
- Finished room: look for an access panel low at the baseboard or high near the ceiling.
- Mobile home: at the water heater or in the underbelly, plus a park riser valve at the lot.
- Apartment or condo: often no main of your own, only stops under each sink and toilet.
Shutting the water off at the meter
If there is no indoor valve, or the indoor valve is the thing leaking, the meter box is the fallback. Lift the lid and there is a shut-off on each side of the meter. The street side is often a b-box: a buried curb stop with a small square nut down a vertical pipe. A curb key reaches it, a long T-handle that grips the nut and closes a quarter turn.
The house side of the meter is yours; the street side belongs to the utility, and some cities fine you for touching it. That nut shears under the wrong tool, so if hand pressure will not move it, call them out.
Gate valve or ball valve, and which way to turn
A ball valve is the lever. In line with the pipe is open, across the pipe is closed. There is no partly-right position, so swing it all the way.
A gate valve is the round wheel that looks like an outdoor spigot. Clockwise closes it, and it takes six or eight full turns, well past the point it feels like it should have stopped. Then open a faucet on the lowest floor; it should trickle to nothing inside a minute. If it keeps running, the valve is not fully closed, or it is not the main.
When the valve is seized or leaks after you close it
A valve that has sat open for fifteen years does not want to move. Work it back and forth gently rather than forcing it one way. A wrench on a corroded gate valve can snap the stem off in your hand, turning a small leak into a full-bore one. Penetrating oil and patience beat muscle.
Weeping around the stem afterward is common, not an emergency; the packing nut behind the handle takes an eighth of a turn tighter. A valve that drips from the body, or will not hold water back once closed, has failed. Shut off at the meter and replace it while the house is dry.
After the water is off
The pipes are still full. Open the lowest faucet in the house and one upstairs to let air in, and the lines empty in a few minutes. If the house will sit cold and empty, drain the tank too. Flushing a water heater covers the shut-down order, because an electric element switched on in an empty tank is ruined. Freezing is the other reason people hunt for this valve in January: thawing frozen pipes and winterizing a sprinkler system. With the water off, get at a leaky faucet or a clogged sink.
