Quick answer
Find the internal stopcock and turn its handle gently clockwise until it stops; do not force it. Open a cold tap to check whether the flow has stopped, and call for help if the valve leaks or will not move.
Before you start
Locate the internal stopcock in advance if possible. It is often near the incoming mains pipe, under the kitchen sink or in a utility cupboard. Tell other occupants before shutting off water. A combi boiler, hot-water cylinder and stored-water system may respond differently, so check your appliance instructions if you are unsure.
Steps to shut off the mains
- 1Place a bucket or towel under the valve if the area is vulnerable to drips.
- 2Turn a wheel handle clockwise by hand, using steady, gentle pressure. For a lever handle, move it a quarter turn so it is across the pipe.
- 3Open a cold tap to release pressure and check whether water continues to run. Some residual water may drain briefly.
- 4When safe to restore the supply, close the tap and turn the stopcock anticlockwise gently. Check the valve and nearby joints for drips.
If the water does not stop
The valve may not be fully closed, may be faulty, or may not be the main stopcock. Do not use a wrench, hammer or lubricant, and do not keep tightening it. If water is escaping, protect belongings and contact a plumber. In a serious leak, ask the water company whether its outside stop tap can be operated safely.
If water is near electrical fittings, do not touch wet switches or equipment. If safe to do so, turn off electricity at the consumer unit and keep clear. For a gas smell, leave the property and call the National Gas Emergency Service on 0800 111 999.
When to call a plumber
- The stopcock will not turn gently by hand.
- Water still flows or leaks after shutting the valve.
- The valve or pipework is corroded, loose or damaged.
- You need help finding the correct valve in a flat or shared building.