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Frozen Pipes: How to Prevent Them, and What to Do If One Freezes or Bursts

Updated 27 October 2026

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The quick answer

Prevent it: lag pipes in the loft, garage and outside walls, cover outside taps, and keep the heating ticking over in a cold snap. If a pipe freezes: turn off the stop tap and warm it gently, never with a flame. If it bursts: stop tap off, heating off, drain the cold taps, keep away from wet electrics, and call a plumber. Know where your stop tap is before you need it.

A frozen pipe is a nuisance. A burst pipe can bring a ceiling down. The good news: most of it is preventable for the price of a takeaway, and ten minutes this weekend.

Find your stop tap now

The stop tap (or stopcock) turns off all the water coming into your home. In most houses it’s under the kitchen sink. It can also be in a downstairs toilet, under the stairs, in a garage or a cellar. In flats it may be in a hall cupboard.

  • Turn it clockwise to close. Give it a go now: old stop taps seize up, and you don’t want to find that out with water pouring through the ceiling.
  • Tell everyone in the house where it is, and label it.

Prevent frozen pipes

  • Lag exposed pipes in the loft, garage, under floors and on outside walls with foam pipe insulation. It slides on and costs a few pounds a metre.
  • Cover outside taps with an insulated tap cover, and if you can, turn off and drain them for winter.
  • Insulate the cold water tank in the loft, if you have one (but not directly underneath it, so a little warmth can rise from below).
  • Fix dripping taps. A slow drip can freeze and block a pipe.
  • Keep the heating on at a low setting during a cold snap, even when you’re out or away. It costs far less than a burst pipe.
  • Open the loft hatch during a very cold spell to let some warm air up to the pipes.

Pipe lagging on Amazon Outside tap covers on Amazon

Most household pipes are 15mm or 22mm. Measure before you buy lagging.

If a pipe freezes

You’ll notice when a tap gives a trickle or nothing at all, often on the coldest morning, and often in a pipe that runs through the loft, garage or an outside wall.

  1. Turn off the water at the stop tap.
  2. Open the cold tap fed by the frozen pipe, so water can escape as it thaws.
  3. Warm the pipe gently, starting from the tap end and working back: a hot water bottle, a towel soaked in hot water, or a hairdryer on a low setting.
  4. Check for leaks as it thaws. Water expands as it freezes, so a frozen pipe may have split.

Never use a blowtorch or any naked flame to thaw a pipe. It’s a common cause of house fires, and can damage the pipe and joints. Keep hairdryers well away from water.

Boiler stopped in the freeze? Check the condensate pipe

If you have a condensing boiler (most installed in the last 15 years), it has a thin plastic condensate pipe that runs outside to a drain. In freezing weather it can freeze, and the boiler stops, often showing a fault code or making a gurgling noise.

  • Pour warm water (not boiling) slowly along the outside section of the pipe, from a kettle that’s cooled a little or a watering can. Boiling water can crack the plastic.
  • Then reset the boiler as your manual describes.
  • If it won’t restart, or you’re not comfortable doing it, call a Gas Safe registered engineer.

Boiler manufacturers have step-by-step guides on their websites. Search for your boiler’s make and “frozen condensate pipe”.

If a pipe bursts

  1. Turn off the water at the stop tap.
  2. Turn off the boiler and central heating.
  3. Open all the cold taps to drain water out of the pipes, and flush the toilets.
  4. Keep away from electrics if water has reached sockets, lights or the fuse box. If you can reach the fuse box safely without touching water, switch it off. If not, leave it and call an electrician.
  5. Catch and mop the water: buckets, towels, and move what you can out of the way.
  6. Call a plumber (or your landlord, if you rent), and your home insurer. Take photos of the damage before you clear up.

A bulging ceiling may be holding water. Keep people out of the room and away from underneath it.

Who’s responsible

Pipes inside your home, and on your side of the property boundary, are usually your responsibility (or your landlord’s). Pipes under the street belong to the water company. Most home insurance covers water damage from a burst pipe, though the pipe repair itself may not be covered. It’s worth checking your policy now.

Get ready in 10 minutes

  • Find the stop tap, check it turns, and label it
  • Lag the pipes in the loft and garage
  • Cover the outside tap
  • Save a local plumber’s number in your phone
  • Keep a few litres of drinking water in case the supply is off

Cold snaps often come with snow and storms, and sometimes power cuts. See our winter car kit and how to keep warm in a power cut.

Frequently asked questions

How do I stop my pipes freezing?

Lag pipes in the loft, garage and outside walls with foam pipe insulation, cover outside taps, insulate the cold water tank in the loft, fix dripping taps, and keep the heating on at a low setting during a cold snap, even if you go away.

How do I thaw a frozen pipe?

Turn off the water at the stop tap, open the cold tap the pipe feeds, then warm the pipe gently with a hot water bottle, a towel soaked in hot water or a hairdryer on a low setting, starting from the tap end. Never use a blowtorch or any naked flame.

Why has my boiler stopped working in freezing weather?

Often it's a frozen condensate pipe: the thin plastic pipe that runs from a condensing boiler to an outside drain. Pour warm (not boiling) water slowly along the outside section, then reset the boiler as the manual describes. If you're not sure, call a Gas Safe registered engineer.

What should I do if a pipe bursts?

Turn off the water at the stop tap, turn off the boiler and heating, open all the cold taps to drain the system, and keep away from electrics that have got wet. Then call a plumber and your home insurer, and take photos of the damage.

Who is responsible for a burst pipe?

Inside the home and on your side of the property boundary, it's usually the homeowner (or the landlord, if you rent). Pipes in the street are the water company's. Check your home insurance, as most policies cover water damage from burst pipes.