Frozen or burst pipes: what to do first

In a hard frost, water standing in a pipe in a cold loft, garage or outside wall can freeze. Ice takes up more room than water, so it can split a pipe or push a joint apart. Often nothing shows until the ice thaws and water starts to escape. A few minutes' preparation, and knowing what to do first, make the difference between a mop-up and a ceiling coming down.

The Consumer Council for Water (CCW) publishes winter advice for households in England and Wales. This guide follows the same approach.

Before it happens

• Find your stopcock and check it turns. CCW says it is usually under the kitchen sink but could be somewhere else, even outside. Our guide to finding your stopcock shows the usual places.
• Lag exposed pipes in the loft, garage and other unheated spaces, and protect the loft cistern. See our pipe lagging guide.
• Cover the outside tap and, if it has an isolating valve inside, turn it off and drain the tap for the winter. See the frost-free outdoor tap guide.
• Fix dripping taps. A slow drip into a cold waste can freeze in the trap or the outside pipe.
• Keep the number of a plumber handy. CCW points to WaterSafe for finding an approved plumber.

Signs a pipe has frozen

CCW lists these signs:

• no water, or only a trickle, from a tap;
• frost on a visible pipe;
• odd smells from taps or drains;
• the boiler or central heating will not start, or gurgles.

If only one tap has stopped, the frozen section is usually on the pipe to that tap, often where it passes through a cold space. If nothing in the house has water, it could be your supply pipe or a problem on the water company's side. Check with neighbours, and contact your water company if they have no water either.

If a pipe has frozen but not burst

1. Turn off the water at the stopcock. If the frozen pipe is on a branch with an isolation valve, you can close that instead.
2. Turn off the immersion heater if you have one, and the central heating, as CCW advises.
3. Open the cold tap fed by the frozen pipe, so water can escape as it thaws. Close it again once the pipe has thawed.
4. Thaw it slowly. Start at the tap end and work back towards the frozen section. CCW suggests a hairdryer on a warm setting, a hot water bottle or a heated cloth wrapped round the pipe.
5. Check for leaks as it thaws, before you turn the water fully back on.
6. Call a plumber if you cannot reach the frozen section, cannot thaw it, or see any damage.

Do not use a naked flame or a blow torch. CCW says so plainly. Do not use a heat gun either. Many homes have plastic pipe or push-fit joints, which heat can soften or damage, and there may be timber, insulation or wiring close by. Keep a hairdryer well away from any water and never use it while standing on a wet floor.

If the boiler has stopped in a freeze, do not take its casing off or try to work on it. Follow the user instructions from the boiler maker, or call a Gas Safe registered engineer. A frozen boiler condensate pipe outside has its own guide: frozen condensate pipe.

If a pipe has burst

1. Turn off the water at the stopcock straight away. If the internal stopcock will not turn, contact your water company about the external one. See stopcocks and water meters.
2. Turn off the central heating and the immersion heater, as CCW advises.
3. Open the taps to drain the system and reduce the flooding. CCW says to turn them back off before you turn the stopcock on again.
4. Catch and soak up water with buckets and towels. Move valuables out of the way.
5. Call a plumber. CCW says you must call in a professional plumber for burst pipes.
6. Take photos or a video of the damage before it is cleared up. Our guide to leak insurance claims covers what to do about the damage itself.

A temporary repair clamp or tape can slow a leak on a straight run of pipe until a plumber arrives, but it is not a repair. Leave the water off.

Water and electrics

Water coming through a ceiling near a light fitting, or pooling round sockets or an electrical appliance, is dangerous.

• Do not touch switches, sockets or appliances that are wet, or that are near the water.
• Only switch off the power at the consumer unit if you can reach it from a dry place without touching anything wet. If you cannot, keep everyone away from the area.
• Call a qualified electrician to check the installation before anything affected is switched back on, even after it looks dry.

Getting the water back on

When the burst is repaired, open the stopcock slowly and watch the repaired section and any joints nearby. Run the cold kitchen tap until it runs clear. On a gravity-fed system, the loft cistern needs to refill before the hot taps work properly again. If a sealed heating system lost water, see our radiator bleeding guide for what the pressure gauge is telling you, and follow the boiler maker's instructions.

Frozen pipe products at Wickes

We haven't tested this. Figures are as the maker states them (checked 13 November 2026).

How long does a frozen pipe take to thaw?

It depends on how cold the space is, how long the pipe has been frozen and where the ice is. Gentle warming can take a while. If you cannot find or reach the frozen section, call a plumber rather than turning up the heat.

Should I leave the heating on to stop pipes freezing?

Keeping some heat in the house during a cold spell helps protect pipes in heated parts of it. It does little for pipes in an unheated loft or garage, which is why lagging matters there.

Will a frozen pipe always burst?

No. Many thaw without damage. But a pipe or joint can split while frozen and only leak as it thaws, so keep the water off and watch it closely while it thaws.