Frozen pipes — how to thaw safely and prevent bursts

Frozen pipes are most common in unheated spaces: loft space (especially roof space water storage tanks and rising mains), garages, outbuildings, pipes in external walls, and condensate drain pipes on boilers during cold snaps.

First turn on the tap supplied by the frozen pipe — as you thaw the pipe, water needs somewhere to go. Leave it open throughout.

Locate the frozen section: look for the part of the pipe closest to an unheated external wall or exposed to the coldest air. Frost-affected pipe sometimes looks slightly deformed or has visible condensation or ice on the outside.

Apply gentle heat starting at the tap end of the frozen section and working back toward the cold area: a hairdryer on medium heat is ideal — keep it moving and do not concentrate on one spot. Warm (not boiling) water poured over the pipe also works well. Hot water bottles and electrician's heat guns (on low) are acceptable alternatives.

Once flow is restored, check immediately for any bursts — a frozen pipe that has split will begin to pour water the moment it thaws. If you find a burst pipe, turn off the mains stopcock immediately.

Prevent recurrence: insulate the vulnerable section with foam pipe lagging (Armaflex or similar, sold in 1m lengths at any DIY store — £1–£3 per metre). For loft pipework, ensure the loft hatch is insulated and close it during cold weather. Leave the loft heating slightly on during a severe frost.