How do I turn the water off at the outside stop tap?
Finding the chamber, using a stop tap key on a valve with no handle, and where responsibility for the pipe changes from the water company to you.
- Difficulty
- beginner
- Time
- 20 min
- Read
- 5 min
- Safety
- caution
Short answer
Look for a small metal or plastic lid in the pavement, verge or driveway near your boundary. Lift it, clear the shaft, and turn the square head at the bottom clockwise with a long-reach stop tap key. Turn slowly and stop if it resists hard — the tap is old and shearing it makes the problem much worse. Everything from that tap to your house is your pipe.
Do this first
The outside stop tap is the shut-off you need when the internal stopcock has failed, when you are replacing it, or when a leak is on the buried supply pipe before the house. It is not a valve for routine use — it is stiff, unlit, buried and rarely touched, and the water company would generally rather you did not operate it at all. But it is also the boundary marker for who pays for a leak, so it is worth knowing exactly where yours is.
Safety
What you'll need
- A stop tap key (long-reach T-bar with a socket end)
- A torch
- A screwdriver or bolster to lift the lid
- A trowel or scoop to clear silt (optional)
- Gloves
Step by step
- Find the chamber.A small square or round lid, often around the size of a hand, set into the pavement, the verge or the driveway close to the boundary. In terraces it may be shared and sit between two houses. Under grass it can be completely buried — feel for it with a rod or check the water company's map, which many publish online.
- Lift the lid.Most have a small keyhole or lip. Prise gently with a screwdriver or bolster. Cast lids in old footways are frequently seized with grit — clear the edges first rather than levering harder.
- Clear the shaft before you reach in.The shaft is often full of silt, leaves, spiders and occasionally water. Scoop it out and shine a torch down. Some chambers have a plastic guard pipe over the tap that lifts out; others contain the water meter as well, sitting above the tap.
- Identify what you are looking at.You want the valve, which has no handle at all — just a square or slotted spindle head. Do not turn anything on the meter itself. If there are two heads, the one nearer the house side of the chamber is usually the supply.
- Seat the key properly before turning.Push the key straight down until the socket is fully over the square head. A key sitting at an angle rounds the head off, and a rounded head means the tap can never be operated again.
- Turn clockwise, slowly, and read the resistance.Expect it to be stiff. Apply steady pressure, not a jerk. Give it a small movement, back off, go again. If it moves at all it will usually keep going. If it feels solid and the key starts to flex, stop.
- Confirm from inside.Open a downstairs cold tap. It should die within a minute or so as the pipe drains. If it keeps running, the tap has not closed or you have turned a neighbour's.
- Reopen slowly and let the air out.Turn anticlockwise, again slowly, and only about three quarters of the way to fully open — that leaves the spindle free rather than jammed against its stop. Then open the taps gradually to let the air out, starting with the lowest cold tap in the house.
Tips
- A proper stop tap key costs very little and is a far better tool than a broom handle with a slot cut in it. Buy one before you need it.
- Photograph the open chamber the first time. Finding it again in the rain at night is much easier with a picture showing which paving slab it is under.
- Water companies generally prefer to operate these themselves and many will do it free on request. If you are not confident, ring them.
- Do not concrete, pave or plant over the chamber. Access to it is a legal easement and you will want it one day.
If it doesn't work
The square head just spins with no resistance
Cause: The head has rounded off, or the internal spindle has parted from the valve — Fix: Nothing more you can do with a key. Report it — the tap is on the company's pipe and they replace it. Meanwhile the internal stopcock is your only isolation.
The chamber is full of water
Cause: Either groundwater collecting in the shaft or a leak from the tap or the connection — Fix: Do not put your hands in blind. If the water is running rather than standing, that is a leak on the company's side of the boundary and they will attend, usually free.
You cannot find any chamber
Cause: Buried under tarmac, turf or a new driveway, or the property is on a shared supply with the stop tap outside another house — Fix: Check the water company's online map, and check with neighbours in terraces and flats. Shared supplies are common in Victorian streets and the tap may serve four houses at once.
It closed, but a neighbour lost their water too
Cause: A shared communication pipe serving several properties — Fix: Reopen it and tell them. On shared supplies you cannot isolate one house from the street — you need an internal valve, and this is a strong argument for getting the internal stopcock working.
Questions people ask
Whose pipe is it once it leaves the chamber?
Yours. The communication pipe from the main to the outside stop tap is the water company's. From the stop tap to your house, including everything buried under your front garden, is the supply pipe and it is the householder's responsibility to repair.
Can I turn off a neighbour's water by mistake?
Yes, easily, especially in terraces where chambers sit on the boundary and shared supplies are common. Confirm by checking your own tap runs dry before assuming you got the right one.
Is there a meter down there too?
Often, yes, on metered properties. It sits in the same chamber, usually above the tap, sometimes in a sealed insulated pot. Do not disturb the meter or its seals.