Three valves and one switch. Between them they stop a flood, a fire and an electrocution, and in most houses at least one of them has never been touched since the building went up.
This is the shortest page in this domain and the one most worth doing something about this week, because every other page here assumes you can isolate the thing that is going wrong.
Do this today, not on the day
Go and physically find all four now. Not on a diagram. With a torch, on your knees, moving the bin and the washing up liquid out of the way. Then do the two things that turn finding them into being able to use them:
- Operate each one. Turn the water off, then on again. Move the gas lever a quarter turn and back. Flip the main switch off for a second. Anything that will not move is a repair job you have just discovered on a quiet Tuesday instead of at two in the morning.
- Time it. How long did it take you to reach the stop tap from the front door? If the answer is more than a minute, the cupboard needs clearing out.
Water
The internal stop tap is the one you will use. It is most often under the kitchen sink, because that is where the main comes into the house, but it can also be in a downstairs loo, a utility room, under the stairs, in a garage, or under a floor hatch. Older houses put it in stranger places than newer ones.
Turn it clockwise to close. The old brass ones are a tap and take several full turns. Newer ones are a lever and take a quarter turn.
Then open a downstairs cold tap and let it run dry. That drains what is still in the pipes, which is the water that would otherwise carry on coming out of the burst.
The external stop tap sits at the edge of the property under a small metal or plastic cover, often in the pavement or the front path. It needs a stop tap key, which is a long T-shaped tool costing a few pounds. It is the backup for when the internal one has failed, and it is also the one that controls the supply to the whole house including anything before the internal tap.
If you have a cold water tank in the loft, closing the stop tap does not empty it, and it will keep feeding the leak for a while. There is usually a separate gate valve on the tank outlet. Find that too.
Gas
The emergency control valve is next to the meter, on the incoming pipe. It has a lever handle, usually painted.
Closed is across. Open is along. When the handle lies in line with the pipe, gas flows. Turn it a quarter turn so it sits at right angles across the pipe, and it is shut. That is the whole rule and it is worth saying out loud once while you are looking at it, because it is not intuitive at three in the morning.
Some older meters have a valve that needs a spanner. If yours does, tape or zip-tie the right spanner to the pipe beside it now. A tool that lives next to the thing it operates is a tool you will actually have.
After the gas has been off, every appliance needs relighting, and anything with a pilot light needs checking. If you are unsure, that is a job for a Gas Safe registered engineer rather than for this page.
Electricity
The main switch is on the consumer unit, the box with all the breakers in it. Not the meter, which belongs to the supplier and is not yours to touch.
Turning the main switch off kills every circuit in the house at once. Individual breakers turn off individual circuits, which is what you want when you are working on one thing and the rest of the house would like to carry on.
Water and electricity together: kill the power first. If water is coming through a ceiling, running down a wall, or anywhere near a socket or a light fitting, the main switch goes off before you go near it with a bucket. See burst pipes.
Know which breaker is which. Most consumer units have a printed list and most of those lists are wrong, because the house has been rewired, extended or reorganised since. Spend twenty minutes with a plug-in lamp and a pen and correct it.
A seized stopcock
The commonest failure on this page. A stop tap that has not moved in fifteen years will often not move at all, or will move and then weep from the spindle, or will snap.
- Exercise it twice a year. Close it fully, open it fully, then back off a quarter turn from fully open. That last quarter turn is what stops it seizing in the open position.
- Do not force a stuck one with a wrench. Old brass goes brittle and a snapped stop tap turns a dry house into a flooded one instantly. Penetrating oil, patience, and gentle back and forth movement.
- If it will not free, get it replaced before you need it. A plumber fitting a modern lever valve is a small job, and it is the single cheapest piece of flood insurance in the building.
- Weeping from the spindle after use usually means the packing has dried out. Often a quarter turn of the gland nut fixes it.
Label them, and tell everyone
Write it down and put it where somebody who is not you can find it. The person who needs the stopcock may be a teenager, a house-sitter, a neighbour with a key, or you at four in the morning in the state where you cannot remember your own postcode.