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How to Prevent Frozen Pipes (and What to Do If They Freeze)

Frozen pipes can burst and flood a home in minutes. Here's how to prevent them before a cold snap, which pipes are most at risk, and how to thaw one safely.

2 min read

A burst pipe is one of the fastest, most destructive home disasters there is — a single break can release hundreds of gallons an hour into your walls and floors. The reassuring part is that freezing is almost entirely preventable with a little preparation before the cold arrives.

Which pipes are most at risk

Cold finds the weak spots. The pipes most likely to freeze are:

  • Uninsulated pipes in unheated spaces — garages, attics, crawl spaces, and basements.
  • Pipes against exterior walls with little insulation.
  • Outdoor plumbing — hose bibs, sprinkler lines, and pool supply lines.

Before the cold: prevention

  1. Disconnect and drain garden hoses, and shut off and drain outdoor faucets. A connected hose traps water that freezes back into the wall.
  2. Winterize irrigation by blowing out the sprinkler lines before the first hard freeze.
  3. Insulate exposed pipes in unheated areas with foam pipe sleeves — cheap and highly effective. Add heat tape for the most vulnerable runs.
  4. Seal drafts near pipes — air leaks in the rim joist or around the foundation let freezing air reach them.
  5. Know where your main water shutoff is so you can stop a flood fast if the worst happens.

During a hard freeze

  • Let vulnerable faucets drip. Moving water resists freezing and relieves pressure.
  • Open cabinet doors under sinks on exterior walls so warm room air reaches the pipes.
  • Keep the heat on, even when away — never below about 55°F. If you travel in winter, prepare the home before you go.

If a pipe freezes but hasn't burst

  1. Open the faucet it feeds — running water and a path for melt helps.
  2. Warm the frozen section with a hair dryer, heat lamp, or hot towels, starting near the faucet and moving toward the cold spot.
  3. Never use an open flame — it can damage the pipe and start a fire.
  4. If you can't find or reach the frozen spot, call a plumber before it thaws and reveals a crack.

If a pipe bursts

Shut off the main water valve immediately, open faucets to drain the system, and call a plumber. Knowing where that valve is — and that it turns — is the difference between a mop-up and a renovation. This is exactly why locating it is a critical first-week task.

Stay ahead of winter

Build your free Owner Tools and we'll schedule freeze-prevention tasks for the right weeks in your climate — outdoor shutoffs, irrigation blow-out, and pipe insulation. No login, no address required.

Frequently asked questions

At what temperature do pipes freeze?+
Pipes are at risk when the outside temperature drops to about 20°F (-7°C) or below, especially uninsulated pipes in unheated spaces or against exterior walls. Wind chill and sustained cold raise the risk, so act before a hard freeze, not during one.
Should I leave faucets dripping to prevent freezing?+
Yes, during a hard freeze. Letting a faucet served by vulnerable pipes drip slightly keeps water moving and relieves pressure, which dramatically lowers the chance of a burst. A pencil-lead-thin stream is enough.
What do I do if a pipe is frozen but not burst?+
Keep the faucet open, then warm the frozen section with a hair dryer, heat lamp, or towels soaked in hot water — working from the faucet end toward the cold spot. Never use an open flame. If you can't reach it or it has already burst, shut off the main water and call a plumber.

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