Where Is My Stopcock? How to Find and Use It
Find your internal stopcock and outside stop tap, learn how to turn the water off, free a stiff valve and why this is worth knowing before an emergency.
If you learn only one thing about your plumbing, make it this: where the water shuts off. When a pipe bursts or a tap will not stop, the difference between a mop-up and a disaster is often thirty seconds and a quarter turn.
What a stopcock is
The stopcock, sometimes called the stop tap, is the valve that controls the water coming into your home from the mains. Turn it clockwise (righty-tighty) and the flow stops. You should be able to shut off the whole house with it.
Where to look
Inside the property
In many UK homes the stopcock sits:
- Under the kitchen sink, often at the back among the pipes.
- Near the front door or in a downstairs cloakroom.
- In an under-stairs cupboard.
- In a utility room or by the boiler.
- In a garage or cellar if the mains pipe enters there.
Follow the cold water pipe that feeds the kitchen tap, as it should lead to the stopcock. In flats, the stopcock may be in a communal riser or meter cupboard.
Outside the property
There is also an external stop tap, often in a small chamber with a lid near the pavement or boundary. It usually belongs to the water company. You need a long key or special tool to turn it, and you should check what you are allowed to do before using it.
How to use it
- Turn the stopcock clockwise until it stops. Do not force it.
- Open the cold taps to drain pipes and release pressure.
- Flush toilets to empty cisterns.
- Turn off any heating that relies on the water supply, if safe to do so, and check the boiler. If there is anything unusual with a boiler, leave it to a Gas Safe registered engineer.
To turn the water back on, open the stopcock slowly anticlockwise and let pipes refill. Check for leaks.
If your stopcock is stiff or stuck
A valve not used for years can seize.
- Move it gently back and forth a little at a time.
- Put a drop of penetrating oil around the spindle and wait.
- Do not use excessive force, as a broken handle makes it worse.
- If it will not budge, ask a plumber to replace it. It is a modest job and will save you stress later.
Test it every six months or so. Turn it off, then on again, and leave it a quarter turn back from fully open so it does not stick.
Label it
Put a clear tag or label on the stopcock, and tell everyone in the household where it is. If you rent, tell your landlord or agent if it is hard to reach or does not work. Our guide to plumbing in a rental explains who handles that.
Other valves worth knowing
- Isolation valves beneath sinks, basins and toilets, which shut off one fixture.
- Appliance valves by the washing machine or dishwasher.
- Cistern and tank valves in the loft.
- Heating filling loop, which is for the boiler circuit and should be left to the boiler's manual. See boiler pressure basics.
Fitting isolation valves where they are missing makes later repairs faster and cheaper.
In an emergency
- Turn off the stopcock.
- If water is near electrics, switch off power at the consumer unit if it is safe to reach.
- Move belongings, mop up and photograph the damage.
- Call a plumber. See frozen and burst pipes for more on what to do.
Worked example: finding it in an unfamiliar house
You have just moved into a Victorian terrace. Start in the kitchen: open the cupboard under the sink and look behind the waste pipe. Nothing there? Check the cupboard under the stairs, where mains pipes often enter. If the house has a cellar, the mains is likely there. Finally, look for a water meter, usually near the stopcock, sometimes in a box outside. Ten minutes of looking now beats ten minutes of panic later.
Common locations by home type
| Home type | Where it often is |
|---|---|
| Victorian or Edwardian terrace | Kitchen, understairs cupboard or cellar |
| 1930s semi | Kitchen or hallway cupboard |
| Modern new build | Kitchen cupboard, utility room or airing cupboard |
| Flat | Kitchen, bathroom cupboard or communal meter cupboard |
| Bungalow | Kitchen or utility room, sometimes the garage |
Testing your stopcock properly
- Turn it off fully and note how many turns it takes.
- Open the nearest cold tap and watch the flow stop.
- Turn it back on and check for drips around the spindle.
- If it weeps, call a plumber rather than forcing it.
What if it does not close fully?
A stopcock that leaks past the seat is common in older homes. It may slow the water but not stop it. Ask a plumber to replace it. It is a short job and worth doing before winter. If the stopcock in a rental is faulty, report it to the landlord in writing; our guide to plumbing in a rental explains the usual split of responsibility.
Teach everyone in the house
Show every adult and older child where it is and which way it turns. A stopcock nobody can find does not help when you are away and someone else is home. Pairing this with frozen and burst pipes gives you a complete emergency routine.
Frequently asked questions
Which way do I turn the stopcock off?
Clockwise, like most taps. A quarter or half turn is not enough on some; it may take several turns.
What if I cannot find my stopcock?
Check under the sink and near the front of the house, and look for the water meter, which is usually near. Ask your water company or a plumber if still not found.
Will turning the stopcock off affect my heating?
It will stop filling tanks and can affect combi boilers. Switch off if unsure, and consult a Gas Safe registered engineer for boiler issues.