Find Your Water Shut-Off Before You Need It

The single most expensive ten minutes in a plumbing emergency is the ten minutes spent looking for the shut-off valve. Water coming out of a failed supply line does not pause while you check the garage. Find it now, on a calm afternoon, and write it down.

Where to look, in order. In most San Jose houses the main house valve is on the street-facing side, at or near ground level, usually within a few feet of an outside hose bib. In slab-built homes from the sixties and seventies it is often on the garage wall, sometimes low and behind whatever has been stacked in front of it for a decade. In older homes with crawlspaces it can be just inside the crawl access. It is a valve on the pipe where the water enters the building, and it will either be a round wheel handle or a straight lever.

There is a second one at the street. Out at the property line there is a meter box, usually a rectangular concrete or plastic lid set into the ground, with the meter and a valve inside. This is the backstop if the house valve fails or you cannot reach it. It often needs a meter key to turn, which is a cheap tool worth owning if you have an older house.

Turn it. Do not just locate it and walk away satisfied. An old gate valve that has not moved in twenty years will very often either refuse to turn or, worse, turn and then fail to seal again. Better to find that out on a Tuesday than during an emergency. If it will not move, do not force it hard enough to snap the stem, because that turns a small job into a bigger one. Just note that it is seized and get it replaced. Swapping a tired main shut-off for a quarter-turn ball valve is one of the cheapest bits of insurance in the whole house.

Individual stops. Every toilet and every sink should also have its own small valve on the wall or in the cabinet. If the problem is confined to one fixture, that is the one to close, and you keep water everywhere else. These seize too, for the same reason. Turn each of them once while you are doing your rounds.

The water heater has its own. On the cold inlet at the top of the tank there is a valve. If the tank itself is the thing leaking, close that. If it is a gas heater, turn the gas control to off as well; if it is electric, switch off its breaker before anything else.

What to do when it is actually happening, in order: shut the water off, kill power or gas to the water heater if that is what let go, then move what you can out of the way and start getting water off the floor. Then call. Damage is mostly a function of how long the water ran, and the first few minutes are worth more than anything we can do once we arrive.

Spend the ten minutes. Take a photo of where the valve is and text it to whoever else lives in the house, because they may be the one home when it happens. If you would rather somebody showed you, we do it as part of any visit. See emergency plumbing, or read about shut-off valves and regulators.