How to Cut Off the Water System in Your House

If there was a soggy emergency at your house, would you know what to do? How does the water system work, where does all the water come from and how do you turn it off? Knowing the answer to these questions could be the difference between a bit of a wet carpet and completely drenched house.

Most houses have a cold water tank, usually in the loft, which feeds most of the taps in the house, plus the lavatory cistern. The tank is filled by the rising main. The only tap fed direct from the rising main is usually the kitchen cold tap, which should always be used for drinking water. A washing machine and garden tap may also be fed by the rising main. A few pre-war and country houses have all the taps, and lavatory cistern, fed direct from the rising main.

Whether you have a burst pipe or you just want to change the washer on a leaky tap, you will need to turn the water supply off first.

For taps that are fed from the cold tank, turn off (clockwise) the gate valve or isolating valve in the appropriate pipe. If may be in the loft. When you have identified it, label it so you don’t forget.

If there is no gate valve or isolating valve on the pipe, you will have to drain the cold-water tank as follows:

1 – Put a piece of wood, like a broom stick, across the top of the tank and tie the ball valve to it so that the valve is out of the water and thus closed. This will stop the water coming in from the rising main.

2 – Turn on the bathroom cold taps until the water stops flowing, and then turn on the hot taps (only a little water will come out of them). There is no need to turn off the boiler as the hot water cylinder will not be drained.

For taps that are fed from the rising main, turn off (clockwise) the main stopcock, and then turn on the tap until the water stops flowing.

If you don’t know where the stopcock is then it is worth going and having a look for it now. In an emergency such as a burst pipe you will want to be able to find it quickly. In most houses is it where the water supply enters the house. It is often under the kitchen sink or in the larder. If the house has a cellar it may be down there. In a bungalow look in the airing cupboard.

In a last resort, if the stopcock is jammed or doesn’t stop the flow of water you may need to turn off the water supply from the outside stopcock in from of your house. It’s under a small square(ish) metal cover either just inside your garden or in the pavement out the front.

The stopcock is below ground level at the bottom of a pipe, so you need a key which you will have to improvise. The stopcock may have a tap in which case a length of wood with a couple of notches at the end would do the trick.