How to stop pipes freezing in a UK winter, how to thaw a frozen pipe safely, what to do immediately if a pipe bursts, condensate pipes on combi boilers, and insurance tips.
When temperatures drop below freezing, water in exposed pipes can freeze and expand, cracking pipes and fittings. The damage often appears when the ice thaws and water pours out. A little preparation prevents most problems.
Prevention
- Insulate exposed pipes in lofts, garages, outbuildings, under floors and on external walls, using foam pipe lagging. Insulate cold water tanks in the loft too, but not underneath them, where warmth from below helps.
- Keep the heating on low when you're away in cold weather, or use the boiler's frost setting.
- Fix dripping taps, because a constant trickle in an exposed pipe can freeze.
- Outside taps: turn them off at the internal isolation valve, drain them, and fit an insulated cover.
- Know your stopcock: find it, label it and check it turns.
- Draughts: seal gaps where pipes run through cold spaces, without blocking ventilation.
- Empty homes: if a property will be empty for a long time in winter, consider draining down the system and check your insurer's conditions.
Signs of a frozen pipe
- no water, or only a trickle, from a tap;
- frost on the pipe;
- a toilet that won't refill;
- a combi boiler showing a fault code in freezing weather (see condensate pipes below).
Thawing a frozen pipe safely
- Turn off the water at the stopcock.
- Open the tap the pipe feeds, so water can escape as it thaws.
- Warm the pipe gently, starting nearest the tap and working back, with a hot water bottle, a hairdryer on a low setting, or towels soaked in warm water.
- Never use a blowtorch or naked flame, and don't pour boiling water on pipes.
- Check for cracks or leaks before turning the water back on.
Combi boiler condensate pipes
Condensing boilers drain acidic water through a plastic condensate pipe, often running outside. If it freezes, the boiler may lock out. If it's safe to reach at ground level, pour warm (not boiling) water along the pipe, then reset the boiler following the manual. Don't climb ladders in icy conditions. Lagging the external section or having it rerouted helps prevent repeats.
If a pipe bursts
- Turn off the water at the stopcock immediately.
- Switch off the boiler and any immersion heater.
- Open all cold taps to drain the system. Flush toilets.
- Protect electrics: if water is near sockets or fittings, or coming through a ceiling near lights, switch off the electricity at the consumer unit if it's safe to do so. Don't touch wet electrics.
- Contain the water with towels and buckets, and move belongings.
- Temporary repair: a pipe repair clamp or self-amalgamating tape can limit damage until a plumber arrives.
- Call a plumber, and take photos for your insurer.
If a ceiling bulges with water, keep away from it; it may collapse.
Insurance
Escape of water from burst pipes is usually covered by buildings and contents insurance, though the excess is often higher for these claims. Insurers may reject claims if you didn't take reasonable care, for example leaving an empty home unheated beyond the policy's unoccupancy period. Report damage promptly.
Renting?
Tell your landlord immediately. Landlords are generally responsible for repairs to pipes and water supply, but tenants should take reasonable steps, such as keeping the heating on in cold weather.
Frequently asked questions
At what temperature do pipes freeze?
Water freezes at 0°C, but exposed pipes are most at risk in prolonged spells below freezing, especially with wind chill.
Should I leave a tap running?
It's generally better to keep the heating on low and insulate pipes than to waste water.
Sources and further reading
Facts checked on 20 October 2026. Spotted an error? Tell us and we will correct it.