Find your stopcock before you need it

Two valves, and they are not the same

The internal stopcock

Inside the property, on the incoming mains, downstream of where the supply enters the building. This is yours, it is your responsibility, and it is the one you need in an emergency. A traditional one is a brass valve with a crutch-shaped or wheel handle; a modern one may be a quarter-turn lever.

The external stop tap

Outside the boundary, usually under a small metal or plastic cover in the path, pavement or driveway. It generally belongs to the water company and sits on their side. It is a backup rather than your primary isolation – it frequently needs a long key, the chamber is often full of silt, and in some older streets one tap serves two properties.

Where to look

In rough order of likelihood in UK housing:

1. Under the kitchen sink. By far the most common. Look at the back of the cupboard where the pipes come up.
2. Downstairs cloakroom or WC, often behind the pedestal or in a boxed-in corner.
3. Utility room, where the incoming main is often routed.
4. Garage, particularly on properties where the main enters through the garage wall.
5. Under the stairs, in a cupboard, sometimes behind coats and vacuum cleaners.
6. Under a floorboard near the front door, common in older terraced houses – look for a small hatch or a board with screws rather than nails.
7. In a cellar, where there is one.
8. In an airing cupboard or a service duct in a flat.
9. Behind a kickboard, which is an unhelpful place people discover during a kitchen refit.

Two useful shortcuts. First, follow the pipe: the incoming main is usually the pipe that goes to the kitchen cold tap, and the stopcock is on it. Second, ask a neighbour with the same house type – on an estate, they are almost always in the same place.

Testing it

Finding it is half the job. Knowing it works is the other half, and a great many stopcocks have not been turned since installation.

1. Turn it fully offClockwise. It should move without excessive force. If it needs serious effort, stop – see below.
2. Check the water has stoppedOpen a cold tap – the kitchen one, since it is fed directly from the main. The flow should stop, or reduce to a trickle and stop.
3. Turn it fully on againAnticlockwise.
4. Back it off a quarter turnFrom fully open. This stops the valve binding in the open position, which is how they seize.
5. Check for weepingAround the spindle, for a few minutes afterwards. A stopcock that has not been turned for years sometimes weeps from the gland once it has been moved. It is usually a simple adjustment or repack.
6. Label itA luggage tag or a marker on the pipe. Obvious to you today; not obvious to a house-sitter, a tenant or a family member at three in the morning.

Do this twice a year. It takes under a minute and it is the entire maintenance regime for the most important valve you own.

If it will not turn

Do not force it. A seized stopcock forced past its limit can shear at the spindle or crack the body, which converts a minor job into an emergency with the water still running and no way to stop it.

Why they seize:

• The gland packing dries out and binds on the spindle.
• The threads corrode, particularly in hard water.
• The washer hardens onto its seat, so the valve will turn but will not seal.
• It has been left hard against the open stop for years and has bound there.

The fix is replacement, carried out under a controlled shutdown at the external stop tap. It is a short planned job. While the main is open, it is worth fitting a quarter-turn lever valve rather than a screw-down stopcock – they are far less prone to seizing and you can see at a glance whether they are open. See stopcocks and mains.

The external stop tap

Worth locating as a backup, particularly if your internal one is doubtful.

• Look for a small square or round cover in the path, pavement, driveway or front garden, often marked with a W.
• Lift the cover – a screwdriver in the slot usually does it. Expect silt and spiders.
• The tap is at the bottom of a vertical chamber and usually needs a stop tap key – a long T-shaped tool. They are inexpensive and worth having before you need one.
• Clear the chamber of silt so you can actually see and reach the tap.
• In some older streets, one tap serves two properties. If yours does, know it now rather than discovering it while turning off a neighbour’s water.
• If the chamber has been paved or tarmacked over, your water company can usually help locate and reinstate it.

Everything else worth knowing where it is

While you are at it, the same ten minutes is well spent on the rest:

Write them on a card and put it somewhere everybody in the house can find. It is the single cheapest piece of emergency preparation there is.