Home › Frozen Pipes
A frozen pipe is a patience question, not a strength question. Rush it and you'll likely have a burst pipe question instead.
Short answer first: close the stopcock before you thaw anything, then warm the pipe gently from the tap end — hairdryer on low, or towels soaked in warm water. Never a naked flame, never boiling water poured straight on. If the pipe has already split, stop and ring 020 4577 2888 any hour.
A tap that's slowed to a dribble or stopped entirely during a cold snap is the classic tell. Check whether the fault appeared exactly when the temperature dropped.
The pattern is the diagnosis here. If a tap ran perfectly well yesterday and produces nothing, or barely a trickle, the morning after a hard frost, freezing is the leading suspect, especially if the affected pipe runs through a loft, garage, outbuilding or exterior wall. Frost patterns on Mid-Ulster nights tend to bite hardest on the Sperrin-facing side of a property and on any pipework that sits outside the heated part of the house.
Feel along the accessible length of the pipe for a noticeably colder section, sometimes with a faint frosting on the outside of metal pipe in a cold room. That's usually where the blockage sits. If the whole system has stopped rather than one tap, the fault is more likely elsewhere — check the stopcock hasn't been knocked, or whether there's a wider supply issue, before assuming ice.
Examiner's note: "worked fine yesterday, frost overnight, nothing this morning" is a complete diagnosis in one sentence. Lead with it.
Stopcock off first, then heat gently from the tap end back toward the blockage. Patience beats power every time.
Close the stopcock before you touch the pipe. This matters because you cannot see whether the ice has already split the pipe wall — frozen water expands as it freezes, and a hairline crack made hours ago will only start leaking once the ice inside melts and lets water reach it. Closing the stopcock first means that if a leak reveals itself, it's a small controlled drip rather than a pressurised flood.
Then apply heat gently, starting at the tap end of the frozen section and working back toward the blockage — this lets meltwater escape forward rather than building pressure against solid ice further along. A hairdryer on its lowest setting is ideal; towels wrung out in warm (not boiling) water and wrapped around the pipe work almost as well and cost nothing. Simply raising the room temperature, if the pipe is somewhere heatable, can be enough on its own given time.
Examiner's note: heat from the tap end, not the middle. Thawing the middle first traps meltwater between two ice plugs with nowhere to go.
No naked flame, ever — not a blowtorch, not a lighter, not a camping stove. And no boiling water poured directly onto the pipe.
A pipe already weakened by expanding ice can crack instantly under the shock of extreme, uneven heat, and a naked flame near a pipe indoors carries an obvious fire risk on top of that, especially near insulation, timber or anything flammable in a loft or garage. There is no version of "carefully" that makes an open flame the right tool here — it's simply off the list.
Boiling water carries the same shock-cracking risk when poured directly onto a very cold pipe, particularly with older metal pipework, and it does little the gentler methods don't already achieve more safely. If you're tempted to speed things up because the house is getting cold, the honest trade is worth making: a slower thaw with the water safely off beats a fast one that turns into an emergency.
Examiner's note: every question on this page that asks "can I speed this up with more heat" has the same answer. No.
Stop thawing immediately and leave the water off. Thawing a split pipe with the mains still connected just books your flood for later.
Once you can see or hear that a pipe has failed — a hiss, a wet patch spreading, water visibly escaping as the ice around a crack starts to soften — the job changes completely. Continuing to apply heat only accelerates the flood, because the ice plug that's currently holding the water back will eventually give way regardless of how gently you're working. Leave the stopcock closed, open the nearest cold tap to relieve any remaining pressure in the pipe, and stop actively thawing that section.
This is where a burst pipe and a frozen pipe become the same problem, and the burst pipe method takes over: water off, taps open to drain what's left, electrics made safe if water is anywhere near them, and then the phone call. Describing "frozen pipe, now split, water off" when you ring tells the plumber exactly what they're walking into.
Examiner's note: a split pipe isn't a frozen-pipe question anymore. Switch scripts — stopcock, taps, electrics, phone.
Lag every exposed pipe before the first hard frost. It's cheap, quick, and the single most effective thing on this whole page.
Foam pipe lagging is sold by the metre in most hardware shops around the town and slides straight over exposed pipework in a loft, garage or outbuilding — no tools beyond scissors and, ideally, some tape at the joins. An afternoon spent lagging the runs you can reach is genuinely the cheapest, most effective plumbing task available to a householder, and it applies just as much to farm outbuildings and long rural supply runs out toward Draperstown and Swatragh as it does to a loft in town.
If a property is going to sit empty over a cold spell — a holiday let, a house between tenants, a farmhouse left over Christmas — keeping the heating on low rather than off entirely, or draining the system down properly if it's going to be genuinely unoccupied for weeks, prevents the whole scenario. Insulating loft tanks and lagging pipes near external walls or under suspended timber floors are the other usual gaps worth checking before the cold really sets in.
Examiner's note: this is the one question on the paper you can answer months in advance. Do it in October, not January.
Anywhere from twenty minutes to a couple of hours, depending on how long the frozen section is and how solid the ice has become. Gentle, steady heat is slower than a hairdryer on full blast pressed against the pipe, but it's slower on purpose — rushing the thaw is exactly what risks splitting a pipe that survived the freeze intact.
Anything outside the heated envelope of the house: pipework in an unheated loft, an integral or detached garage, an outbuilding, or running through an external wall with thin or missing insulation. Outside taps and their internal shut-off valves are also common victims, since they're often the pipe run furthest from any source of heat.
Foam pipe lagging is inexpensive and widely available from hardware shops in town — a few metres costs a fraction of a single emergency call-out, and fitting it yourself over an exposed run is a straightforward afternoon job for most householders. It's one of the few plumbing tasks on this site that doesn't require a professional at all.
Not usually as a category, but insurers do sometimes ask whether reasonable precautions were taken — adequate heating, lagged pipes, or draining a system if a property was left empty in cold weather. Read your policy's specific wording on escape of water and unoccupied properties, and keep the receipt if you lag pipes afterwards as a preventative step.
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