What is a stopcock? How to turn off your water

Finding the stopcock in your new home should be one of the first things you do on moving day. In a plumbing emergency, it can be the only thing standing between you and hundreds of pounds in damage. 

Here’s everything you need to know, including how to find your stopcock and how to use your stop tap in an emergency.

What is a stopcock?

A stopcock (sometimes called the stop tap or internal stop valve) is a shut-off valve that controls the flow of water into a home. 

In an emergency, or when repair work needs to be done, the stopcock can be used to shut off the home’s water supply. If you have a burst pipe, for example, this will stop the leak until it can be repaired, preventing further damage. 

Most homes actually have two of these devices fitted – an internal stopcock and an external stopcock. The internal stop valve should be accessible to you, and is the one you should use in an emergency. The external stop valve will be used by your water supplier, such as Thames Water in London. 

How do I find my stopcock?

There are a few locations in your home where your stopcock might be positioned, including:

• Under the kitchen sink (the most common option)
• Under the floorboards (usually in older homes)
• In an airing or utility cupboard
• In the cupboard under the stairs
• In the garage
• In a basement or cellar

If you’re having trouble finding your stop tap, check your home’s inventory report, as it should be noted there. Alternatively, if you rent, your landlord or property manager should be able to help you find it.

What if I have a shared water supply?

Some properties, such as houses that have been converted into flats, have a shared internal water supply. In this case, the stopcock should be in a shared area, such as the entrance hall. 

Top tip! Be sure to let the other residents know if you need to turn off the water supply, as their properties will also have their water supply disrupted.

How do I use a stopcock?

Using a stop tap is very simple; it works a lot like an ordinary tap.

To turn your water off:

Turn the top of the valve clockwise until you feel firm resistance. You might have to turn it several times, but you shouldn’t have to force it closed. If you have someone else to help, have them run a tap or watch the leak to tell you when it has stopped. 

Top tip! It might take a minute or more for the water to stop completely as there will be some water in your pipes and plumbing

To turn your water back on:

Turn the tap in the opposite direction, anti-clockwise, and wait for the flow of water to return. Be sure that you’ve closed any taps and gaps you might have opened in your plumbing before you do!