Frozen pipes: how to thaw them safely
Last reviewed 2 October 2026 by the Swansea Plumbing Quotes team
The short answer
If a tap gives no water on a freezing morning while others work, a pipe on that run has probably frozen. Turn off the stopcock first in case the pipe has split. Then warm the pipe gently, starting from the end nearest the tap, with a hot-water bottle, warm towels or a hairdryer on a low setting. Never use a blowtorch or any open flame. If a condensing boiler stops with a fault code in a frost, its outside condensate pipe may be frozen: pouring warm (not boiling) water over it often fixes it.
Step by step
- Turn the stopcock off before thawing, in case the frozen pipe has split.
- Open the tap the pipe feeds, so melting water can escape.
- Warm the pipe gently from the tap end back towards the frozen section.
- Check carefully for leaks or splits as it thaws.
- When it is clear, turn the water back on slowly and look again for drips.
Frozen boiler condensate pipe
Most modern boilers have a plastic pipe running outside to a drain. In a hard frost it can freeze and stop the boiler. Pour warm, not boiling, water along it, then reset the boiler as its manual describes.
Preventing it
Lag pipes in lofts, garages and on outside walls, fix dripping taps, and keep the heating on low when you are away in winter. Outside taps should be isolated and drained before the first frost.
When to get help
If a pipe has split, or you cannot find or reach the frozen section, request quotes for a plumber.
General guidance only. If anyone is in danger, or you smell gas, call the emergency services first.