How to keep pipes from freezing — and what to do if one already has
A burst pipe is one of the few household failures that can do serious damage in an afternoon, and almost all of it is preventable with work that takes a single autumn Saturday. The physics are worth understanding, because they explain why the standard advice is what it is.
Before the first freeze
Disconnect every garden hose
This is the highest-value item on the list and the one most often forgotten. A hose left attached traps water in the spigot and in the pipe behind it, inside the wall. Frost-free sillcocks are designed to drain — but only if nothing is attached holding water in the valve. Disconnect, drain, and store the hoses, then shut off and drain any interior supply valves feeding exterior spigots.
Insulate the exposed runs
Foam pipe sleeves cost very little and install by hand. Prioritise unheated spaces: crawlspaces, garages, attics, unfinished basements, and any run against an exterior wall. Seal the joints so there are no bare gaps — an insulated pipe with an uninsulated elbow still freezes at the elbow.
Close the air leaks
Cold air moving across a pipe freezes it far faster than still cold air. Open foundation vents, gaps where cables and pipes pass through the rim joist, and unsealed crawlspace doors are common culprits. Caulk and expanding foam are inexpensive and immediately effective.
Find and label the main shutoff
Locate it, turn it to confirm it moves, and make sure everyone in the household knows where it is. During an actual burst, the difference between knowing this and hunting for it is measured in gallons per minute. Label it, and photograph it.
Deal with the sprinkler system
Irrigation lines and backflow preventers need to be blown out or drained before winter in freezing climates. A cracked backflow preventer is an expensive spring surprise, and it is entirely avoidable.
During a hard freeze
Let a slow drip run from faucets served by vulnerable pipes, especially those on exterior walls or at the far end of the run. Both mechanisms matter: moving water resists freezing, and an open tap gives pressure somewhere to go if ice does form.
Open the cabinet doors under kitchen and bathroom sinks on exterior walls so household heat can reach the supply lines. Keep the garage door closed if any plumbing runs through it. And do not set the thermostat back overnight during an extreme cold snap — the savings are small and the downside is not.
If you are leaving the house for a stretch of winter, set the heat no lower than the mid fifties, arrange for someone to check in, and consider shutting off the main water and draining the system for longer absences. Most catastrophic water damage happens in empty houses, because the water runs for days instead of minutes.
If a pipe is already frozen
The signs are a faucet that yields only a trickle or nothing at all, visible frost on an exposed pipe, or an odd bulge in a section of pipe. Act quickly but carefully.
Open the faucet
Do this first, before applying any heat. It gives melting water and released pressure somewhere to escape, and running water at the tap will tell you the moment the blockage clears.
Apply gentle heat from the faucet end backwards
A hair dryer, a heat lamp at a safe distance, an electric heating pad, or towels soaked in hot water. Start at the fixture and work toward the frozen section, so meltwater always has a clear path out rather than being trapped behind more ice.
Check every other fixture in the house
If one pipe froze, the conditions that caused it apply elsewhere. Run every tap. It is far better to find a second frozen line while you have the tools out than after it has split.
Stand by the shutoff as it thaws
If the pipe cracked while frozen, the leak will not appear until the ice melts and flow resumes. Be ready to close the main immediately. This is the moment your earlier five minutes of labelling pays for itself.
- Disconnecting hoses and insulating exposed pipe
- Sealing air leaks in crawlspaces and rim joists
- Gentle thawing of an accessible frozen line
- Locating and labelling the main shutoff
- A pipe you cannot reach — inside a wall, ceiling, or slab
- Any pipe that has split or is leaking
- Repeated freezing in the same location, which is a design problem
- Sprinkler blowouts and backflow preventer service
The clean-up is the expensive part
If a pipe does burst, close the main, cut power to affected areas from a dry position, and start photographing before you move anything. Then get the space dry fast — fans, dehumidifiers, and professional drying if the volume is significant. Water damage becomes a mould problem measured in days, not weeks, and the remediation costs far more than the plumbing repair.
What homeowners argue about online
Every cold snap produces the same Reddit argument: is letting faucets drip actually necessary, or is it folk wisdom that wastes water? The objection is usually that a utility asked people not to, or that a drip cannot possibly stop water from freezing.
The second half of that objection is fair — moving water freezes too, just more slowly. But it misses the mechanism that matters. What splits a pipe is not the ice; it is the pressure that builds between a growing ice plug and a closed tap, which is why pipes so often fail at a point nowhere near where they froze. An open faucet relieves exactly that pressure. That is the real reason for the advice, and it is why it works even when the pipe does freeze.
So the useful version is narrower than the usual telling. You do not need every tap in the house running through a mild night — that is where the water-waste complaint is justified. During a genuine hard freeze, run a slow drip on the fixtures fed by vulnerable pipes: exterior walls, crawlspaces, and the far end of the run. The water costs a few cents. A burst pipe in a wall does not.
Write it down while it’s fresh
Winterising is a checklist that repeats every single year and gets forgotten in exactly the same way every year. A recurring reminder that arrives before the first hard frost — not after — is the entire difference between prevention and repair.
- Where the main shutoff is, with a photo — and where the water meter is
- Which pipes are in unheated spaces and which have been insulated
- The date you disconnect hoses and blow out sprinklers each year
- Any pipe that has frozen before, and exactly where
- Plumber contact details and past invoices
- Dated photos and receipts from any water event, for your insurer
This is the part almost everyone skips, and it’s the part that pays. The next time this happens — or when a warranty claim, an insurance adjuster, or a buyer’s inspector asks — the answer is already written down. That is what homwarden is built to hold: maintenance, appliances, warranties, receipts, and records, filed with the equipment they belong to.
Common questions
At what temperature do pipes freeze?
Water freezes at 32°F, but pipes inside a heated house are insulated by the structure around them. Risk rises sharply during sustained temperatures well below freezing, particularly for pipes in unheated spaces, exterior walls, crawlspaces, attics, and garages, and where wind can reach them.
Should I let faucets drip during a freeze?
A slow drip on fixtures served by vulnerable pipes is a widely recommended precaution. Moving water is harder to freeze, and an open faucet relieves the pressure that builds between an ice blockage and a closed tap — which is what actually bursts pipes.
How do I thaw a frozen pipe safely?
Open the affected faucet first so melting water has somewhere to go, then apply gentle heat starting at the faucet end and working back toward the frozen section. Use a hair dryer, a heat lamp, or towels soaked in hot water. Never use an open flame or a propane torch on a pipe.
Why does a pipe burst where it is not frozen?
The ice plug itself rarely splits the pipe. As it grows, it pushes water toward the closed faucet, and pressure builds in that trapped section. The pipe fails at its weakest point in that stretch, which is often well downstream of the ice.
General maintenance guidance only. It is not a substitute for an inspection, a licensed contractor, an engineer, your insurer, the manufacturer’s instructions, or local code. When the stakes are gas, fire, structure, or standing water near electricity, stop and call a professional.