How to Thaw Frozen Pipes, and Stop Them Freezing Again

Most frozen pipes can be prevented with an afternoon’s work in the autumn. The houses in this part of London make it worth doing: tall Victorian homes with cold lofts, cellars under the pavement and long pipe runs on outside walls give frost plenty of places to find.

Before the cold arrives

• Lag the pipes in the loft and the cellar. Foam pipe insulation is cheap and slips straight on. Pay most attention to pipes near the eaves, roof hatches and air bricks.
• Insulate the loft tank, if you have one, on the top and sides but not underneath, so a little warmth rises from the room below.
• Protect outside taps. Turn off the isolating valve inside if there is one, open the outside tap to drain it, and fit an insulated cover.
• Fix draughts where pipes pass through outside walls or under suspended timber floors.
• Find and test your stopcock, so you can shut the water off quickly if something splits.

If you are going away

An empty house in a cold spell is the classic burst pipe. Keep the heating on low or on its frost setting, leave the loft hatch open a little on very cold nights so some warmth reaches the tank, and ask a neighbour to look in. For a long trip, consider turning the water off at the stopcock and draining the system.

Thawing a frozen pipe safely

1. Open the tap that the frozen pipe feeds, so water can escape as the ice melts.
2. Start at the tap end and work back towards the frozen section, so meltwater has somewhere to go.
3. Use gentle heat: a hairdryer on low, a hot water bottle or towels soaked in warm water.
4. Never use a naked flame or boiling water. Old pipes, joints and timber do not take sudden heat well.
5. Watch for leaks as it thaws. A pipe can split while frozen and only start leaking once the ice melts.

When to call us

Call 07862 142953 if a pipe has split, if water is coming through a ceiling, or if you cannot find or reach the frozen section. Our page on frozen pipes explains how we thaw, repair and protect them, and burst pipe repair covers what happens if a pipe has already gone.