What is a stopcock and what does it do?

If you discover water cascading into your home, it’s good to know where to find your stopcock. Learn what you can do if your home’s at risk of water damage.

Eve Powell
Eve Powell
Updated 2 February 2022  | 3 mins read

What is a stopcock?

A stopcock is a type of tap or valve that’s used to control and shut off the flow of water into your home. For this reason, they’re sometimes known as stop taps or stop valves.

You’ll need to know where to find it in your home if you need to turn your water off to do maintenance or if you have a plumbing emergency.

By using your stopcock to shut off the water, you could prevent a leak from causing serious water damage in your home.

Key points

  • Your stopcock acts as an off switch for the mains water supply in your home
  • You need to know where your stopcock is so you can access it in an emergency
  • Most stopcocks are under the kitchen sink, but they can sometimes be difficult to find
  • Check your stopcock and turn it on and off twice a year to prevent it from seizing up

External stopcock

Your outside stopcock controls the cold water that goes from the water main in your street into the pipe that supplies your home.

It’s often found just outside your property’s boundary and is usually under a small metal cover (with a ‘W’ or the word ‘Water’ on it) on the street near your home.

The external stopcock belongs to your water supplier, so you may need to use a qualified plumber or get permission to turn the water off, particularly if the water supply is shared with other homes.

Internal stopcock

The internal stopcock controls the water at the point where it goes from the mains supply pipe into your home.

This is the point where you can shut the water off - however, some stopcocks can be in unusual places, especially in older properties, so make sure you know where to find yours.

Most people should be able to turn their internal stopcocks on and off themselves and this can usually be done by hand.

What does it look like?

Stopcocks come in different shapes and sizes and usually look like a tap or a lever, but without a spout.

You’ll find the stopcock placed between two lengths of pipe where it acts as a connector - so turning it off will block the flow of water.

Depending on your home, the stopcock is sometimes red or coloured, and it often has a typical T-shaped tap handle, or it can be wheel-shaped or look like a lever.

What does a stopcock do?

A stopcock controls the flow of mains water supply that comes into your house. It’s always on and allows water to be supplied into your home as and when you need it.

But the stopcock also lets you control your water supply.

You’ll need to find your stopcock and close it when you need to turn off your water or if you’ve got a plumbing emergency, like a leak or a burst pipe.

When your stopcock’s turned off, any taps, showers and appliances that use water, like washing machines and dishwashers, won’t work.

If you do need to turn your stopcock off, you may want to make sure your boiler is turned off as well. This is to stop it getting damaged.

Why is it so important for your home?

If your home has frozen pipes, a leak, or an escape of water, you’ll need to turn off the water supply as soon as you can to minimise any damage.

Any delay in finding and turning off your stopcock can have a huge impact if there’s water coming into your property.

Stopcocks can seize up, leak, or stop working, so it’s important to check that yours is functioning properly and fix any problems before disaster strikes.

Be aware that it’s a condition of most home insurance policies that your home is well-maintained - so if there’s a leak and you couldn’t shut off your stopcock, your claim could be refused.

Will my home insurance cover a leak?

Yes, water damage is usually covered as standard on your buildings insurance policy but whether you can claim will depend on what caused it.

For example, if your leak happened because of wear and tear, then you may not be covered.

If you discover a leak, you’ll need to turn your stopcock off straight away and run all your taps to empty your system of water.

Take photographs of the damage, as these might help with a claim, and contact your insurers as soon as possible. You may need to get a plumber to come and assess the problem.

Where can I find my stopcock?

Your stopcock will usually be found close to where the water pipe enters your home. But this can vary, and they can be tricky to find, especially if renovation work has covered it up.

Some of the most common places to find your stopcock include:

  • Under the kitchen sink
  • In the airing cupboard or near your boiler
  • Behind larger appliances, like fridges and dishwashers
  • In a downstairs toilet or bathroom
  • Near the gas meter
  • Under the stairs
  • In the utility room
  • In a communal corridor or hallway cupboard, if you live in a shared building
  • Under floorboards by the front door

What if I can’t find my stopcock?

If you’ve checked all the likely places and still can’t find your stopcock there are a few things you can do.

For example, if you’ve got plans of your property your stopcock will normally be marked on these as ‘SC’, which can help you to track it down.

Another option is to speak to a neighbour - stopcocks in properties that were built around the same time are often put in a similar place, so find out where theirs is.

And if you still can’t find your stopcock, your water supplier should be able to help you.

How do you turn your water off?

Before you start, make sure all your appliances that use water are turned off.

Once you’ve found your stopcock, you should be able to easily turn it off by turning the tap, lever, or wheel clockwise.

Your water should now be turned off - but check this by running a tap to see if it runs dry.

Tips for stopcock maintenance

Keeping your stopcock well maintained can help if you need to make a claim. Make sure you:

  • Know where your stopcock is so you can access it in an emergency
  • Check your stopcock is in good working order at least twice a year
  • Turn off your stopcock as soon as possible if you discover a leak or frozen pipes
  • Turn your stopcock regularly to stop it from seizing up or jamming
  • Use some oil or lubricant to try and loosen it if your stop tap is difficult to turn,
  • Contact a plumber if your stopcock’s not working, is leaking, or you can’t get it to turn

How to reduce the risk of escape of water

Water damage or ‘escape of water’ is one of the most common home insurance claims, but there are some things you can do to help minimise the chances of needing to make a claim, including:

  • Know where your stopcock is and check it regularly to make sure it’s working
  • Lag or insulate your pipes to help prevent them from freezing during the winter months
  • Keep pipes warm by setting a minimum thermostat temperature of 12°C
  • Check for any visible signs of leaks, such as damp or discoloured patches on ceilings
  • If you’re doing DIY, use a pipe detection device before you start drilling
  • Regularly check pipe connections to appliances as well as toilets, sinks, baths, and showers
  • Fix dripping taps as soon as possible to prevent problems in cold weather

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