Frozen pipes: how to thaw them and stop them bursting
If a tap gives no water in freezing weather, a pipe feeding it is probably frozen. Leave the tap open, then warm the pipe gently with a hot water bottle, warm cloths or a hairdryer on low, working from the tap end back. Never use a naked flame. If the pipe has split, turn off the stop tap, drain the system by opening the cold taps, switch off the electrics near the leak and call a plumber.
Key facts
- First sign
- No water from one tap in freezing weather
- Safe heat
- Hot water bottle, warm cloths or a hairdryer on low
- Never use
- A blowtorch or any naked flame
- Frozen condensate pipe
- Warm (not boiling) water on the outside section
- If it has burst
- Stop tap off, drain the cold taps, call a plumber
Where pipes freeze first
| Symptom | Most likely cause |
|---|---|
| One tap gives no water | The pipe feeding it runs through a cold space |
| Boiler stops and gurgles in a freeze | The condensate pipe outside has frozen |
| Leak appears as the weather warms | A pipe split when frozen and leaks once thawed |
| No water anywhere | The incoming supply has frozen, often where it enters the property |
How to thaw a frozen pipe
- 1Open the tapOpen the tap the frozen pipe feeds so melting water can escape.
- 2Warm from the tap endApply gentle heat starting nearest the tap and work back along the pipe.
- 3Use safe heat onlyA hot water bottle, warm cloths or a hairdryer on low — never a naked flame.
- 4Check for splitsWatch the pipe as it thaws; turn the stop tap off immediately if it leaks.
Signs a pipe has frozen
Frozen pipes are most common in lofts, garages, outbuildings, under-floor voids and on outside walls. Look for:
- • No water, or a trickle, from one tap while others work.
- • Frost on the outside of a pipe, or a pipe that looks swollen.
- • A condensing boiler that stops in cold weather with a gurgling noise and a fault code.
How to thaw a frozen pipe safely
Open the tap the pipe feeds, so melting water has somewhere to go. Warm the pipe gently, starting nearest the tap and working back, using a hot water bottle, towels soaked in warm water or a hairdryer on a low setting. Never use a blowtorch or any naked flame. Check the pipe for splits as it thaws: a crack often only starts leaking once the ice has melted.
Frozen boiler condensate pipe
Condensing boilers drain water through a plastic pipe that often runs outside. If it freezes, the boiler stops. Pour warm, not boiling, water along the outside section of the pipe, then reset the boiler following the manufacturer's instructions. If it keeps freezing, the pipe may need rerouting or insulating.
If the pipe has burst
Turn off the stop tap, open the cold taps to drain the pipes, switch off the boiler and immersion heater if the leak is on hot water or heating pipework, and switch off electrics near the water. Then call a plumber.
Stopping it happening
Most frozen pipes are preventable for very little money:
- • Lag pipes and tanks in lofts, garages and outbuildings.
- • Isolate and drain outside taps before winter, or fit an insulated cover.
- • Keep the heating on low, or on its frost setting, when you are away.
- • Fix dripping taps — a slow drip in an unheated space freezes easily.
- • Know where your stop tap is and check that it turns.
Need this doing rather than reading?
We cover the GU, KT, SW, CR, SM, TW, BR, RH and BN postcode areas, 24 hours a day, 7 days a week, including bank holidays.