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How to stop a water leak

By Rebecca Milligan

So you’ve got a water leak. Before your plumber arrives, there are a number of things you can do to reduce any damage

The first thing to do is to turn the water off. Your home’s main stopcock will turn the entire system off. It is often at the back of the stairs, under the sink or in a larder. But you do not need to shut down the entire system if you can turn off the water nearer to the source of the leak. It is good practice for all water using appliances or fixtures in your house to have an isolation valve attached, so you can shut off the water to that area alone.

Most shut-off valves will turn off in a clockwise direction. You can turn anything with a handle on it (a lever valve) across the pipe to switch the water flow off – these valves may have an arrow on to help.

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The different types of leak

You’ll need to take different action depending on what type of leak you’re dealing with. Is the water flow intermittent or constant? If it’s constant then it is likely to be a main pipe, if it is intermittent, it’ll be something like a shower or washing machine. Remember that water travels; it doesn’t always come out immediately above where it is leaking.

  1. Radiators – if your radiator is leaking, turn the valves off at the end of the radiator. If it appears to turn endlessly without doing anything, it is a balancing valve, so you’ll need to take the plastic bit off and use pliers or similar to turn the brass bit underneath clockwise.
  2. Toilet overflows – as a store of water, your loo should have an isolation valve that you can close with a screwdriver or a finger turn fastening. If the washer in the float valve is leaking, you can stop the water going into the cistern by closing the isolation valve. This should be located close to the cistern inlet.                                            
  3. Hot taps - if you’ve got a combi-boiler that provides all the hot water in your home, you can turn off the cold feed going in to the boiler to cut off the hot water.
  4. Cold water - you can either turn it off using the main stopcock (usually located at the back of the stairs, under the sink or in a cupboard) or the inflow to a water meter if you have one.                                     
  5. Tank overflows – this may be caused by a washer in the ball valve not shutting off properly, which in turn may be due to limescale. Sometimes just giving the ball valve a  wiggle can loosen the limescale and get it working again. Only examine your tank if there is safe access through your loft.

Is it really an emergency?

If you’ve got a leak and it is causing damage, naturally you want it fixed and fast. But a dripping tap or overflow may not even fill a bucket overnight and will not cost you much, even on a water meter. In these cases it is not worth calling an out-of-hours emergency repair service – though unscrupulous traders won’t tell you that. If the water is draining away freely and not causing damage, wait until the morning when the cost will be much lower.

To help fix your leak, find an accredited Which? Trusted Trader plumber in your area.

And prevention is always better than cure. So find out where your main stopcock is and test it annually to make sure it works. If you have a plumber coming round to repair a leak, use it as an opportunity to ask them to check over your system.

They can find out whether you need any more isolation valves installed and identify any that you already have, so you can find them quickly in an emergency.

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