How to find and turn off your stopcock
Knowing where your stopcock is, and checking it turns, is the most useful thing you can do before a leak or burst pipe happens. Here's where to look and how to use it.
- Time
- 10 minutes
- Difficulty
- Easy
- Steps
- 7
- Checked
What you’ll need
- Torch
- Outside stop valve key, if you need to use the outside valve Search Amazon for water stop tap key
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Safety first
- Don't force a stiff stopcock with a long bar or hammer. You can break the spindle or the pipe and make things far worse.
- If water is near electrical sockets or fittings, don't touch them. Switch the electricity off at the consumer unit if you can do so safely.
Step by step
-
Step 1: Look where the water pipe comes in
The inside stopcock (also called a stop tap or stop valve) is usually just after the mains water pipe enters your home. Common places: under the kitchen sink, in the airing cupboard, under the stairs, near the front door, under floorboards, or in a garage, utility room or cellar.
Next: step 2 -
Step 2: Know what it looks like
It's usually a brass tap with a handle on a copper or plastic pipe. Some newer homes have a blue lever valve instead.
Next: step 3 -
Step 3: Turn it off
Turn the handle clockwise until it stops. It may take several turns. Don't use excessive force. Water may keep coming from taps for a few minutes while the pipes empty. Open the cold tap in the kitchen to check.
Next: step 4 -
Step 4: Turn it back on
Turn it anticlockwise to open. It can take a few minutes for water to flow properly. Opening it slowly helps avoid a bang in the pipes.
Next: step 5 -
Step 5: If you live in a flat
There may be a stopcock inside your flat and a communal one where water enters the building. Find out from your landlord or managing agent where both are.
Next: step 6 -
Step 6: Use the outside stop valve if you need to
If you can't find the inside one or it won't turn, the outside stop valve is usually under a small cover in the pavement or driveway near your boundary. You'll need a stop tap key. Turn it clockwise. If your supply is shared, this may cut off your neighbours as well, so warn them.
Next: step 7 -
Step 7: Test it regularly
Stopcocks that aren't touched for years can seize up. Thames Water suggests checking yours regularly, turning it off and on, so it works when you need it.
Tips
- Tie a label on the stopcock and tell everyone in the house where it is.
- In a burst pipe emergency, once the water is off, switch off any electrics near the leak at the consumer unit, and turn off your boiler or immersion heater.
When to call a professional
If your stopcock is stiff, leaking or broken, ask a plumber to replace it, ideally before you need it. Look for one approved through WaterSafe. If water is leaking from the pipe on the outside of your property, or from the outside stop valve, contact your water company.
Questions people ask
Which way do I turn a stopcock to turn the water off?
Clockwise to close, anticlockwise to open.
My stopcock won't turn. What can I do?
Don't force it. Use the outside stop valve if you need the water off urgently, and ask a plumber to replace the inside one.
Will turning off the stopcock stop my central heating?
No. Your heating carries on, but a combi boiler won't give hot water without the mains supply. If there's a leak, it's often sensible to turn the boiler off too.
Sources
Checked 9 October 2026. We wrote this guide in our own words, using:
- Thames Water: how to find and use your inside stop valve (thameswater.co.uk)
- Thames Water: how to find and use your outside stop valve (thameswater.co.uk)
- WaterSafe: find an approved plumber (watersafe.org.uk)
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Printed from howtoguides.uk/guides/how-to-find-and-turn-off-your-stopcock/ · Checked 9 October 2026 · General information only. For gas, electrics, structural work, medical, legal or money decisions, use a qualified professional.