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How to turn off your water supply

Stop valves, often known as stopcocks, are simple tap like devices that control the flow of water into and around your home.

Your property will typically have two stop valves: one external and one internal.

When you have a water leak, you’ll often be advised by your water company to access and turn off one or both of these in order to help determine the velocity of your leak, prevent water loss or protect your property from damage.

There is no difference between a stop valve, a stopcock and a stop tap. They are simply different words for the same thing.

Finding your outside stop valve

Your outside stop valve controls the cold water supply going into your property.

It determines the flow of water from your property boundary through your mains supply pipe and up to your internal stopcock. You should only need to use your external stop valve if you suspect you have a leak on this supply pipe.

You can often find your outside stop valve on the pavement or road just outside of your property. It will likely be hidden beneath a metal cover with the name of your water company or a simple description stamped on top.

Your external stopcock is usually located in the same area as your water meter. If you are still unsure where this is, we recommend that you contact your water company directly.

Older houses, flats or apartment buildings may share a mains supply with other properties, in which case the stopcock could be located further up the road. Just remember to warn your neighbours before you turn it off!

Note that in most instances turning off an external stop valve would be done by your water company or a plumber. If you were to try it yourself, you may need to purchase a specific valve or a universal stopcock key.

Finding your inside stop valve

The most fastest and most effective way to stop the flow of water into your home is to turn off your supply using the internal stopcock.

It is a legal requirement for all UK properties to have at least one internal stop valve and it is the responsibility of the homeowner to maintain and replace it.

Your internal stop valve controls water distribution throughout your property and is situated at the end of your mains supply pipe.

The internal stop valve is most often found under your kitchen sink, but this is not guaranteed. If you can’t locate it under your sink, other common places to find it are under the stairs, in your garage or in an airing cupboard.

If you still can’t find your internal stopcock, we recommend contacting your water company or a local plumber.

Shared and communal buildings

If you live in a shared building, such as a block of flats, your water supply may be controlled by a communal inside stop valve.

In other cases, individual flats or apartments may have separate stopcocks present in a communal area or within each flat itself. If you are unsure, we recommend contacting the management company of your building or even asking a neighbour or your landlord (if renting).

Turning off your internal stopcock

Once you’ve found your stop valve, you should be able to turn it off by hand by turning the tap clockwise. This will stop all water supply to your home until you turn it back on again.

You can test if it has worked by turning on a water tap in your kitchen or bathroom, but be aware that residual water contained in the pipes may continue to flow for a few minutes before the supply dries up completely.

To restart your water supply, turn your internal stop valve anti-clockwise.

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