Where Is the External Water Stopcock?

Where to look, in order

Thames Water describes the outside stop valve as normally under a cover on the path or the road, sometimes in the same area as your water meter. In practice, work through these places from your front door outwards.

• Your own front path or front garden, a metre or two inside the boundary, especially if you have a water meter.
• The pavement directly outside your house, usually within a metre or so of your front wall or gate line.
• The pavement outside a neighbour’s house. Terraced streets often have a row of covers, and yours is not always the one in front of your door.
• The kerb edge or the road itself, less often, particularly on older streets.
• At the end of the road or in a communal area, where several homes share one supply.

If you are looking because water is pouring through a ceiling right now, check the inside stopcock first. It is quicker to reach, and Thames Water says the outside valve is for emergencies such as a leak on the supply pipe. How to turn off a stopcock covers that.

What the cover looks like

External stop valve covers are small, usually around the size of a hand or a paperback book, and often square or rectangular. Older ones are cast iron and may be marked W, WATER or SV, or carry the water company’s name. Newer ones are plastic or metal with a hinged or lift-off lid. Meter chambers are larger, often round or rectangular and sometimes marked METER.

Do not confuse them with gas valve covers, usually marked GAS, or with telecom and drainage covers, which are larger. If you are unsure whether a cover is yours, look for a pipe running towards your house beneath it, or ask the water company to confirm.

Covers are often buried under a layer of soil, gravel or moss in front gardens, or paved over during driveway work. If you have a meter but cannot see the chamber, check your water bill or the meter installation letter, which sometimes describes its location.

How to open the cover and turn it off

Lift the cover with a flat screwdriver or a thin bar in the slot at the edge. Underneath you will usually find a narrow shaft, sometimes a plastic tube, going down to the valve. The valve can be anywhere from a few inches to around a metre below ground, which is why you normally need a key.

A stopcock key is a long steel bar with a T-handle at the top and a forked or socketed end that fits over the valve handle. DIY and plumbing stores sell universal keys for roughly £15 to £30, around a metre long, which is enough to reach well below pavement level. If you do not have one, a neighbour may, and it is worth buying one before you need it.

Lower the key onto the valve head, feel for it seating, and turn clockwise to close. Thames Water gives the same direction: clockwise to turn off, anticlockwise to turn on. Then check a cold tap inside the house slows and stops.

• Silt and debris often fill the shaft. Clear it with a small trowel or gloved hand so the key can reach the valve.
• A meter chamber may contain a quarter-turn valve beside the meter. Turn it until the handle sits across the pipe.
• If the valve will not move with firm pressure on the key, stop. Do not stand on or hammer the key. A broken valve in the pavement is the water company’s repair, but it will leave you with no way to isolate your house until they attend.

Shared supplies: warn the neighbours first

Many London homes do not have their own outside stop valve. Older terraced houses often share one supply pipe between several properties, and converted houses and blocks of flats normally have a single valve for the building. Thames Water warns that if your home is on a shared supply, turning the water off will also turn your neighbours off.

Knock or leave a note before you close it, and do not leave it shut longer than you need. If you live in a flat, your inside stopcock may be in the flat, in a communal cupboard, or on a riser in the stairwell; the building managers or freeholder should know.

Under the Water Supply (Water Fittings) Regulations 1999, a pipe supplying water to two or more premises in common must have a stopvalve each occupier can reach. If you share a supply and nobody knows where that valve is, that is worth raising with the water company or your freeholder.

Who owns the external stopcock, and what if it’s broken?

The outside stop valve belongs to the water company. In Thames Water’s area, they own the main in the street and the communication pipe up to your boundary, which is where the outside valve normally sits. From there to your house is your supply pipe, along with everything inside, including your inside stopcock. Who owns the water pipe to your house explains the split.

So if the outside stop valve is missing, buried beyond reach, seized or leaking, report it to the water company; a broken cover in the pavement is theirs too, but one inside your front garden is usually yours to replace.

That creates the awkward case: you have a leak inside, the inside stopcock will not turn off, and the outside valve is seized or cannot be found. Thames Water’s own advice for that situation is that the quickest way to stop the water is to contact a plumber. Where the pipe is suitable, an engineer can freeze a section of it with a pipe-freezing kit to form an ice plug and stop the flow, then fix the leak and the stopcock. See emergency help when you can’t stop the water.

Find it now, before you need it

The worst time to look for an outside stop valve is at night with water coming through a ceiling. Spend ten minutes finding yours on a dry afternoon, clear the shaft, check a key reaches it, and make a note of where it is.

While you are at it, check the inside stopcock turns. If it is stiff, our guide to a stopcock that won’t turn will help, and if it has seized or will not shut off, get it replaced while there is no emergency. Stopcock repair and replacement covers the visit; the £60 call-out applies at any hour, and the repair price is agreed with you on site before any work starts.