When a pipe bursts or a fitting fails, you do not want to start emptying cupboards and guessing where the water turns off. Every homeowner, tenant and landlord should know where the main internal stopcock is, make sure it is accessible and show other adults in the property how to use it.
The stopcock—also called an internal stop tap or stop valve—controls the mains water entering your property. Closing it will not repair a leak, but it can greatly reduce the amount of water escaping while help is arranged.
Where should I look?
The internal stopcock is normally fitted close to the point where the incoming water pipe enters the building. Start with these common locations:
- under the kitchen sink, usually at the back of the cupboard;
- inside a nearby kitchen or utility cupboard;
- under the stairs or in a ground-floor cloakroom;
- in a garage, cellar or service cupboard;
- close to the front door in some flats and converted properties; or
- beneath a removable floorboard in an older home.
Do not confuse it with a small isolation valve serving one tap, toilet or appliance. A traditional stopcock is usually a brass valve on the incoming cold-water pipe with a T-shaped or wheel-style handle. Some properties have a modern lever valve instead.
How to test it safely
Choose a normal daytime when help is available if a problem is discovered. Turn the handle clockwise gently to close it. Then open a cold tap and check that the flow reduces and stops. Water already stored in pipework may continue briefly.
Reopen the valve slowly by turning it anticlockwise. Check the valve and nearby joints for drips afterwards. Never overtighten it at either end of its travel.
What if it is stiff or seized?
Stop if the handle will not move with gentle hand pressure. Do not use a hammer, long wrench or extra leverage, and do not dismantle the valve while the supply is live. Old or corroded pipework can crack, and a broken stopcock can turn a precautionary check into an active leak.
A plumber can assess whether the valve can be serviced or should be replaced. It is far better to discover a seized stopcock during a planned check than during a burst pipe at night.
What should I do when a leak happens?
- Protect people first. Keep away from water near sockets, lights, appliances or the consumer unit. Do not touch wet electrical fittings.
- Isolate the source. Use a nearby appliance or fixture valve if you can identify it safely. For a larger or unidentified leak, close the main internal stopcock clockwise.
- Relieve the pressure. Open a cold tap after closing the stopcock and allow the remaining water to drain into the sink.
- Limit the damage. Move possessions, use buckets or towels where safe, and stay clear of a bulging ceiling.
- Call for help. Explain where the leak is, whether the water is isolated and your location. Photographs can help identify the likely parts needed.
If the internal stopcock cannot be found or operated, contact a plumber and your water supplier. An outside stop valve may serve the property, but it can be shared and may belong to the water company. Do not force it, excavate it or assume it isolates only your home.
A useful landlord check
At every change of tenancy, confirm that the internal stopcock is visible, labelled and working. Record its location in the property information, show the tenant how to close it safely and make sure stored belongings do not block access. This simple check can reduce damage to the property below as well as the affected home.
Need help with a stopcock or leak?
If your internal stopcock is seized, dripping or difficult to access, arrange a check before an emergency. For plumbing help across Essex, call Ricky on 07939 013120 or email Essexemergencyplumbing@gmail.com.