Frozen Pipes — How to Prevent and Thaw Them
If a pipe has already burst (you will see bulging, cracks, or water pouring out when it thaws), turn off the mains stopcock immediately and call a plumber.
Frozen pipes are one of winter's most costly surprises — a burst pipe can damage your home and run up repair bills reaching thousands of pounds. The problem happens when water inside pipework freezes solid during prolonged cold spells, usually in exposed areas like lofts, under floorboards, or on outside walls. Older properties and those in rural areas are particularly vulnerable, but any home can be affected if pipes aren't properly insulated or heated during a freeze. This guide walks you through recognising when a pipe has frozen, how to safely thaw it without causing further damage, and the preventative measures that genuinely work. If you're dealing with a burst pipe that's already caused water damage, stop reading and call a qualified plumber immediately — water damage only gets worse with time.
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Most likely cause & what to check
If you suspect a pipe has frozen (no water from a tap, visible frost on a pipe), act quickly before it thaws and potentially bursts.
Turn off the main stopcock as a precaution — if the pipe has cracked or burst, you don't want water pouring out when it thaws.
To thaw a frozen pipe: apply gentle heat using a hair dryer, heat gun on a low setting, or hot water bottles. Start from the tap end and work back towards the coldest section.
Never use a blowtorch or open flame on pipework — this is extremely dangerous and can cause fires or damage plastic pipes and joints.
Open the tap as you thaw — this releases pressure and lets you know when the ice has cleared (water will start to flow).
Once thawed, turn the stopcock back on slowly and check for any leaks along the frozen section. Even small cracks can appear after freezing.
To prevent frozen pipes in future: lag all exposed pipes in lofts, outbuildings, and outside walls with foam pipe lagging (£3–5/metre). Keep your heating on a low setting (at least 12°C) during cold snaps even if you're away. Drain and turn off outside taps before winter.
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Frequently asked questions
How do I know if a pipe is frozen rather than just broken?
If you've got no water from a tap but the mains stopcock works fine and other taps still flow, a frozen pipe is the likely culprit. You might also see frost or ice on visible pipework, especially in unheated areas like the loft or under the sink. Turn off the stopcock as a precaution and attempt to thaw the section — if water suddenly flows when it warms, the freeze was the problem.
Is it safe to use a heat gun to thaw my pipes?
Yes, a heat gun on a low or medium setting is one of the safest methods for thawing pipes — far better than a blowtorch. Work slowly from the tap backwards towards the frozen section, keeping the gun moving to avoid overheating any one spot. Never point it directly at plastic fittings or joints, as these can warp or crack.
Can frozen pipes burst even if I thaw them carefully?
Yes — when water freezes it expands, and even careful thawing won't always prevent cracks that already exist in the pipe walls. This is why checking for leaks immediately after thawing is essential; small weeping leaks can turn into major problems within days if left untreated.
Should I leave my heating on when I go away in winter?
Absolutely — keep your heating set to at least 12°C even when you're not home, particularly if you're away for more than a few days during a cold snap. Turning off heating to save money during winter can cost you thousands in burst pipe damage, so it's a false economy.
What's the cheapest way to prevent frozen pipes?
Pipe lagging foam is your most cost-effective solution at around £3–5 per metre and takes just an hour or two to fit around exposed pipes in lofts and under floors. Draining outside taps and isolating them before winter also costs nothing and removes a common problem point entirely.
If my pipes freeze once, will they keep freezing?
Not necessarily — it depends on whether you've addressed the root cause. If the pipe lacks proper insulation or your heating is too low, yes, it will likely freeze again next winter. Installing lagging and maintaining adequate background heating will solve the problem for most homeowners.