How to Prevent Frozen Pipes in Winter

A burst pipe is one of the few home failures that can flood several rooms in an afternoon. What makes it maddening is how avoidable it usually is. Freezing weather doesn't have to mean frozen pipes, and a few dollars of insulation plus a couple of habits during cold snaps prevent the vast majority of them.

Preparing for winter in the warmer months is exactly the right instinct, because the fixes are calmer and cheaper when nothing is at stake. Let's cover why pipes actually burst, which ones to worry about, and what to do if one freezes anyway — including the point where you should stop and call a plumber.

Why frozen pipes burst#

It's tempting to picture the ice splitting the pipe by pushing outward, but that's not quite what happens. When water freezes it expands, and as ice forms and grows inside a pipe it pushes the remaining liquid water ahead of it, toward the nearest closed tap. In that trapped section, pressure climbs and climbs. The pipe usually fails there — often somewhere the ice never even reached.

That detail changes how you think about prevention. You're not just trying to keep ice from forming; you're trying to keep pressure from building. That's why letting a faucet drip during a hard freeze works so well: an open tap gives the water somewhere to go, so pressure can't build to the bursting point even if a little ice forms.

The damage arrives later, on the thaw. A pipe can crack while frozen and stay sealed by the ice itself, then release once everything warms and the water starts flowing again. So a quiet freeze can become a loud flood hours after the cold has passed.

Know which pipes are at risk#

Not every pipe needs attention. The vulnerable ones share a trait: they run through spaces that don't get much heat.

• Pipes in unheated garages, basements, crawlspaces, and attics
• Supply lines in exterior walls, especially on the north side
• Outdoor faucets, hose bibs, and sprinkler lines
• Any pipe near a draft, a vent, or a gap where cold air sneaks in

Walk your home with this list in mind before winter and note the trouble spots. The kitchen or bathroom sink on an outside wall, the pipe crossing an uninsulated garage, the hose bib you forgot to drain last year — those are where your effort belongs. Everything cozy inside the heated envelope of the house is generally fine.

Prepare before the cold arrives#

Autumn is the deadline, but the work is pleasant to do earlier. Start outside: disconnect garden hoses, drain them, and shut off and drain the lines to outdoor faucets. A hose left attached traps water in the bib, and that's a classic first casualty of a freeze.

Then insulate the at-risk pipes indoors. Foam pipe sleeves cost little, slide right on, and cut with a utility knife. For the worst spots — an exposed run in a crawlspace, say — thermostatically controlled heat tape adds active protection, though anything electric near plumbing deserves care and a read of the instructions.

Find your main water shutoff valve today, while it's warm and calm, and make sure everyone in the house knows where it is and how to work it. In the two minutes after a pipe bursts, that knowledge is worth more than any tool you own.

Seal the drafts that feed cold air to your pipes. A bit of expanding foam or caulk around the gap where a pipe enters the house keeps the local temperature up right where it matters. This kind of small, preventive work sits naturally alongside the other cold-weather tasks on a seasonal home maintenance checklist.

Get through a cold snap#

When a genuine freeze is forecast, a few temporary habits carry you through:

1. Let a faucet on an exposed line drip slowly, both hot and cold if it's fed by pipes at risk.
2. Open cabinet doors under sinks on outside walls so warm room air reaches the plumbing.
3. Keep the heat on and steady, even in rooms you'd usually let cool, and don't set the thermostat back too far at night.
4. If you're traveling, leave the heat at a safe minimum rather than off, and consider having someone check in.

These cost almost nothing and pull you through the coldest nights. The dripping tap in particular does double duty — it keeps water moving and relieves the pressure that actually causes bursts.

Leaving town during winter deserves its own plan, because an empty house has no one to notice trouble and no body heat or cooking to warm the rooms. If you'll be away for more than a day or two in freezing weather, keep the heat set no lower than the mid-fifties Fahrenheit rather than switching it off to save money — the potential flood dwarfs any heating saving. Ask a neighbor or friend to look in every day or two, and leave them the location of the main shutoff and a phone number to call. For a longer absence, the safest option is to shut off the water at the main and drain the system entirely, so there's nothing left in the pipes to freeze while you're gone.

If a pipe freezes anyway#

Sometimes prevention isn't enough, and you turn on a tap in the morning to a trickle or nothing. Don't panic, and don't reach for an open flame — a blowtorch on a pipe is how a frozen pipe becomes a house fire.

Open the affected faucet so water and steam can escape as the ice melts. Then warm the frozen section gently, working from the tap end back toward the blockage, using a hairdryer, a heating pad wrapped around the pipe, or towels soaked in hot water. Warm the room too, and be patient; gentle and steady beats fast and risky every time.

If you can't find the frozen section, can't reach it, or the pipe has already burst, shut off the water at the main and call a plumber. This is squarely a licensed-pro moment. The same goes for pipes inside finished walls, anything involving your water heater or the gas that fires it, and any repair you're not confident in — a good starting point for that side of things is how to flush your water heater, which covers the parts you can maintain yourself and the parts you shouldn't.

The reassuring part is how much of this you control. A weekend of insulating and draining in the warm months, a couple of good habits during freezes, and a clear plan for the worst case — that's the whole defense. Do it once and winter stops being a threat to your plumbing and goes back to being just weather.