Where to find the internal and external stopcocks, how to turn them off safely, what to do if one is stuck, and how to drain the system in a leak emergency.
If a pipe bursts, the first thing you need to do is turn off the water, and in that moment you do not want to be searching for the stopcock. Spend five minutes finding and testing yours now. This guide explains where to look, how to turn it off and what to do if it will not move.
Internal and external stopcocks
- The internal stopcock (stop tap) controls the cold mains supply into your home. You are responsible for it.
- The external stop valve is usually under a small cover in the pavement or garden near your boundary. It is generally the water company's responsibility and may serve more than one property. Use it only in an emergency, and you may need a special key.
Where to find the internal stopcock?
It is usually where the mains water pipe enters the house. Common places:
- under the kitchen sink;
- in a downstairs toilet or utility room;
- in a cupboard under the stairs or in the hallway;
- near the front door, sometimes under a floorboard or behind a panel;
- in flats, it may be in a cupboard, in a shared area, or inside a riser. Ask your landlord or managing agent.
Look for a valve on a pipe, usually with a tap-style handle or a lever.
How do you turn it off?
- Turn the handle clockwise to close it ("righty tighty"). A lever valve is off when the lever is across the pipe.
- Open the cold tap in the kitchen to check the water has stopped. It may take a moment to run dry.
If it won't turn
Stopcocks that have not been used for years often seize.
- Do not force it with a large wrench, which can break the valve or the pipe.
- Try gently working it back and forth a little at a time.
- A little penetrating oil on the spindle may help.
- If it still won't move, ask a plumber to replace or service it, ideally before you have an emergency.
Keep it working
Once or twice a year, turn the stopcock off and on again to stop it seizing. After fully opening it, turn it back a quarter turn so it does not stick in the open position.
In a leak emergency: step by step
- Turn off the stopcock.
- Turn off the electricity at the consumer unit if water is near electrics, sockets or light fittings, and only if it is safe to reach the consumer unit. Do not touch electrics with wet hands.
- Turn off your boiler or immersion heater.
- Open the cold taps to drain the cold water system. If you have a cold water tank in the loft, opening cold taps upstairs (and flushing toilets) drains it more quickly.
- Open hot taps to drain the hot water. Do not turn off the water to a hot water cylinder and leave the heating on.
- Contain the water with buckets and towels, and move valuables.
- Call a plumber, and, if you rent, your landlord. Take photos for your insurer.
Isolating valves: the smaller taps
Many appliances and fittings, such as toilets, washing machines and sinks, have their own small isolating valves on the pipes feeding them. Turning the slot a quarter turn across the pipe stops water to that fitting only, so you can do repairs without turning off the whole house.
Frequently asked questions
Does the stopcock turn off the heating?
No. It stops the mains water supply. Your heating system and any stored water still need to be dealt with separately.
My water pressure is low after turning it back on
Make sure the stopcock is fully open. If pressure stays low, contact your water company.
Sources and further reading
Facts checked on 20 October 2026. Spotted an error? Tell us and we will correct it.