How to find and turn off your stopcock
Last reviewed 2 October 2026 by the Swansea Plumbing Quotes team
The short answer
Your internal stopcock is usually under the kitchen sink, where the cold supply enters the house. It can also be in a downstairs toilet, the airing cupboard, under the stairs or below floorboards near the front door. Turn it clockwise until it stops. If it will not move, do not force it with a tool. Use the outside stop tap (usually under a small cover in the pavement or front path) or call Dŵr Cymru Welsh Water on 0800 052 0130.
Step by step
- Look under the kitchen sink first, for a brass or plastic tap on the pipe coming up through the floor.
- Turn it clockwise (righty-tighty) until it stops. Then open a cold kitchen tap to check the water has stopped.
- To drain the pipes, run the cold taps upstairs and flush the toilets.
- If you have a hot-water cylinder, switch off the immersion heater and the boiler while the water is off.
- Once it is fixed, turn the stopcock back on slowly to avoid knocking and splashing.
If the stopcock is stuck
Stopcocks that are never used seize up. Don’t use a wrench. Old ones can snap and make the leak worse. Turning it fully on and off once or twice a year keeps it working. A plumber can replace a seized one with a modern quarter-turn valve.
The outside stop tap
Most Swansea houses also have a stop tap under a small metal or plastic cover outside, near the boundary. It usually needs a long key. Welsh Water can help if you cannot find it or it serves more than one home.
Know where it is now
Find your stopcock before you need it, and tell everyone in the house where it is. Label it if it is hidden in a cupboard.
When to get help
If water is near electrics, keep clear. Turn the electricity off at the consumer unit only if you can reach it safely, then request urgent quotes.
General guidance only. If anyone is in danger, or you smell gas, call the emergency services first.