What is a stopcock and how to find it

It is vitally important to know where your stopcock is and how to turn it off.

A stopcock (sometimes called a ‘water mains tap’ or ‘stop tap’) = a tap that controls the mains water supply coming into your house.

If you have a burst pipe or internal leak, you should find your stopcock as soon as possible in order to prevent the water from causing some serious damage before the plumber arrives. In most cases, turning off the stopcock will stop the leak, but it will also block the entire water supply to your house.

It’s not often that you might need to use your stopcock, but it’s important to be able to access it quickly in an emergency.

Are you wondering - what does a stopcock look like? Where is my stopcock? You’re not alone. According to research, less than half of 18 - 34 year olds in the UK know what they are. So, we’re here to change that. Here’s a rundown of everything you need to know.

Internal and external stopcocks

Most homes have both an internal and external stopcock. The external stopcock controls the flow of water that serves your street into your house through a supply pipe. If the supply pipe ruptures or leaks, the external stopcock will need to be turned off to stop water soaking the floor and to allow repairs to take place.

The internal stopcock (also called a house water stopcock) controls the water from the supply pipe as it enters your property. Turn it off and it will shut the water off in your property.

What does a stop tap look like?

Stopcocks/stop taps look like a tap , but without the spout. You’ll find it between two lengths of pipe, as it’s a connecting piece - this allows the stopcock to block the flow of water when it’s closed off.

Stopcocks can take different shapes and sizes so checkout what they look like here.

Where is the stopcock in my house?

Can’t find your stop tap? No problem, we’ll help you out.

External stopcock: often located under a cover on the road or path just outside the boundary of your property. You might also find it in the same area as your water meter. If your house is old or you share a supply with your neighbours, you might find it at the end of your road. If you’re on a shared supply, remember that turning it off will turn off the water for everyone else, so make sure to let your neighbours know first. The external stopcock will usually be marked by a metal cover stamped with the word ‘stopcock’ or simply ‘W’.

Internal stopcock: this can be a bit trickier to locate, especially in properties that have been renovated as they often get moved or covered over. The most common place to find it is under the kitchen sink. Not there? Head to the airing cupboard, scour the bathroom, the cupboard under the stairs, the gas meter, the utility room and root through your cupboards. If you live in a block of flats, you might find it’s in a communal corridor with the other flats’ stopcocks. If you have the plans to your property, the stopcock will usually be marked ‘SC’. In older buildings, it can sometimes be found under the floorboards near the front door.

Still can’t find your stopcocks? It’s always worth asking your neighbour where theirs is, as it might be in a similar place. In an ideal world, you should ask where the stopcocks are before you move in, no matter whether you’re renting or buying. If you don’t already know, see if you can find out from the previous owners, estate agent or landlord. Checkout other questions you should ask when veiwing if you’re renting here.

It’s also worth noting that some properties only have internal stopcocks and, in rare instances, some don’t have any stopcocks at all. It is now a legal requirement to have at least one stopcock, so you’ll need to get a plumber in.

How to turn off your stopcock

Stopcocks can seize up if they’ve been in the same position for a long time, so once you find one, make sure to test it’s working. If it’s stiff, you might be able to loosen it with a bit of WD40.

Turning off an internal stopcock:

This can usually be done by hand, although you may need a set of pliers to fully close it.
Turn the tap handle clockwise, this should mean the mains are shut.
Your water supply should now be stopped, check by turning one of the main water taps in your house (no water should come through).
To turn it back on, turn the handle anti-clockwise.

Turning off an external stopcock:

It’s less likely that you’ll need to turn off the external stopcock; this job is usually carried out by the plumber, but it’s best to be prepared, so…
You might need a stopcock key, which is a long metal tool with a T-bar handle at one end and a fitting at the other that slots around the valve.
Insert the key into the valve.
Turn the key clockwise until the T-bar handle is across the pipe, this should shut the mains off.
When you’re ready, turn it anti-clockwise to open it again.

Now that you know your stopcocks are working properly, you’ll be ready for any emergency. If you do have a leak, you should turn the water supply off as quickly as possible and then call a plumber to fix the problem.

If you turn your stopcock off, it’s a good idea to turn all your machines that have a water supply off too, such as your boiler, washing machine and dishwasher.

One final tip…

Whilst we’re on to the topic of sudden, unexpected events, do you have Home Emergency cover? It’s an added extra to home insurance policies and, in the instance of a leak in your home, would usually cover the cost of a call-out plumber, charges, parts and materials needed to fix the issue. It would also save you the headache of trying to find a contractor - all you would need to do is call the Home Emergency phone number (available 24/7) and they’ll sort it all for you. Check out ‘What is Home Emergency cover?’ to find out more.