How to thaw a frozen pipe


In Consumer Advice

We have seen the first flurries of sleet and snow this year and it looks like the current cold conditions are here to stay. With weather warnings in place across the country, many of us will be experiencing the type of freezing conditions ripe for plumbing disasters.

When the temperatures drop below freezing, the water within exposed or uninsulated pipework can freeze. In plumbing systems this can limit water supplies to taps, showers and toilet cisterns. In heating systems this can limit water supplies to your boiler or heat source. As an added complication, water expands when frozen, so this can lead to boiler damage, cracked or burst pipes and substantial leaks.

The Chartered Institute of Plumbing and Heating Engineering (CIPHE) offers the following advice when dealing with the havoc that temperatures in the minuses can cause:

  • If a pipe freezes or has burst, turn off the mains water supply at the stop-valve - often sited under the kitchen sink.
  • If there isn’t an internal valve or you don’t know where it is, turn off the water at the external valve - often found under a cover in your garden or path.
  • If you have a frozen pipe running from a storage cistern (that is not controlled by a valve) and you suspect the pipe has split, you should empty the cold water storage cistern by opening the cold water on the bath, shower and taps - then call a professional plumber.
  • If your frozen pipe isn’t split, thaw it out by applying hot water bottles.
  • If any part of the hot water system is frozen or affected by a burst pipe, there could be a risk of explosion if the boiler (or other heat source) is kept alight, so ensure it is turned off, or for solid fuel systems, extinguish the fire.
  • Be careful - although water may be flowing from taps, other parts of the system may still be frozen.
  • Don’t try to thaw the pipe too quickly as there may be splits in the pipe which are not immediately noticeable.
  • Never use a naked flame to thaw a pipe.
  • Always start thawing a pipe at the end nearest the tap.
  • Only ever attempt to thaw pipes that are easily accessible and/or at ground level. If you ever don’t feel competent thawing the pipe yourself, call in a professional.

Burst pipes need to be dealt with calmly and swiftly. If the pipe is burst, you have turned off the mains water and the leak cannot be controlled immediately, open all COLD water taps and flush the WC so that the pipework and storage system drains quickly. DO NOT OPEN HOT TAPS. Turn off the central heating system and, if it uses a solid fuel boiler, allow the fire to die out. Switch off any electric immersion heater and then call a professional plumber.

Don’t have a regular engineer? You can find a plumbing and heating system professional online at, by phoning 01708 472791 or emailing