Frozen Pipes: How to Thaw Them Safely and Stop Them Bursting

Spot the signs early

A frozen pipe usually announces itself. Taps run slowly or not at all, there’s no water from one tap while the others work, or you notice frost on an exposed pipe in a loft, garage or outside wall. Pipes in unheated spaces and along north-facing walls freeze first. If it’s been below freezing and the water has stopped, assume a frozen pipe until you know otherwise.

What to do straight away

Turn off the water at the mains so nothing floods if the pipe has split — if you’re not sure where it is, our guide to finding and turning off your stopcock will help. Then open the affected tap so the water has somewhere to go as the ice melts, and check the pipe and the ceiling below for any sign of a leak.

How to thaw it safely

Warm the pipe gently, starting nearest the tap and working back along the pipe. A hairdryer on a low setting, a hot water bottle or a warm towel wrapped around the pipe all work. Never use a blowtorch, heat gun or any naked flame — it can damage the pipe, start a fire, or turn the ice to steam inside a sealed length of pipe. Keep the tap open while you do it and be patient: it can take a while.

If it has already burst

Ice expands as it freezes and can split the pipe, but you often won’t see the damage until it thaws and water starts to escape. If water appears, keep the mains off and follow our steps for a burst pipe in the first ten minutes. If you’re worried about damage or can’t reach the pipe, this is a plumbing emergency worth a call.

Stop it happening again

Lag exposed pipes in lofts, garages and under floors, and insulate outside taps. In a cold snap keep the heating on low rather than off, and leave the loft hatch open so warm air reaches the tank and pipes. If you’re going away in winter, leave the heating on at a low background setting rather than switching it off. If your boiler loses heat when it freezes, a frozen condensate pipe is a common cause — see our winter boiler breakdown checklist.