How to keep pipes from freezing
Insulate the pipes on outside walls and in unheated spaces, seal the drafts on them, and on the coldest nights let a faucet trickle and open the cabinets.
Which pipes freeze
The ones near outside walls, in crawlspaces and in the attic, Illinois Extension says. A pipe inside a heated room rarely freezes; a pipe in a cold space with air moving across it freezes first.
Before the cold comes
- Insulate those pipes. Foam pipe sleeves are cheap and slip on. For a run that still freezes, Extension's next step is heat tape listed by UL.
- Seal the leaks near them. Close gaps that let cold air reach the pipes where they run.
- Take care of the outdoor faucets. See winterizing outdoor faucets and hoses.
- Find the main shutoff. If a pipe does burst, closing it is what limits the damage.
On a freezing night
- Let a faucet trickle, hot and cold, from a faucet on an outside wall.
- Open the cabinet doors under sinks on outside walls so room heat reaches the pipes.
- Keep the heat on, set no lower than 55 degrees, overnight too.
The freeze check sorts these by tonight's forecast and where your pipes run.
Why it is worth the trouble
An eighth-of-an-inch crack in a pipe can release up to 250 gallons of water a day, according to Illinois Extension. A trickling faucet costs a little water; a split pipe in a wall costs a ceiling.
The steps for pipes and water
- Find the main water shutoff, and show everyoneIf a pipe bursts, closing the main valve is what stops the damage. Make sure everyone in the house knows where it is and how to turn it.
- Insulate the pipes most likely to freezeThose near outside walls, in crawlspaces and in the attic. Foam sleeves made for pipes slip on; UL-listed heat tape is the next step for a run that still freezes.
- Seal the cold air leaks near pipesA draft on a pipe freezes it faster than still cold air. Seal gaps where cold air gets in around the pipes.
- Open the cabinet doors under sinks on outside wallsIt lets the room's heat reach pipes that have no insulation of their own.
- Let a faucet trickle at nightHot and cold, from a faucet on an outside wall.
- Have someone check the house every day, or drain the waterSomeone stops in daily to make sure the heat is still on. If no one can, shut off and drain the water system (not an indoor fire sprinkler system, which must stay on).
Sources
Drafted on October 26, 2026 with a language model from the pages listed above, each opened that day, and sampled by the editor after publication. Every figure is computed by the same code the tools run, and a test fails the build if one stops matching.
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