Why do pipes freeze and burst?
Water expands as it freezes, and that puts enormous pressure on the pipe holding it, metal or plastic. That's how the American Red Cross explains it, and the pressure is what splits pipes.
A pipe often bursts in the cold but doesn't leak until it thaws. Check exposed pipes as temperatures rise after a freeze.
Which pipes are most likely to freeze?
Outdoor lines, pipes in unheated spaces, and pipes on exterior walls freeze first. The Red Cross lists hose bibs and sprinkler lines, pipes in basements, crawlspaces, attics, garages and under cabinets, and pipes running along poorly insulated exterior walls.
If your home has a crawlspace, the pipes under the floor are the ones to protect first.
How do I stop my pipes freezing?
Before a cold snap, drain outdoor hoses, shut off and drain the supply to outdoor spigots, and insulate exposed pipes. During the freeze, open cabinet doors under sinks, let a cold tap drip, and keep the thermostat at the same setting day and night, per the Red Cross.
- Disconnect and drain garden hoses
- Close the indoor shut-off to outdoor spigots and open the spigot to drain it
- Fit foam sleeves or UL-listed heat tape to exposed pipes
- Keep the garage door closed
- Open kitchen and bathroom cabinet doors on exterior walls
- Let a cold tap on an exposed pipe drip overnight
- Going away? Leave the heat on, set no lower than 55°F
How do I thaw a frozen pipe safely?
Open the tap, then warm the frozen section with a hair dryer, an electric heating pad, a portable space heater kept at a safe distance, or towels soaked in hot water. Never use a blowtorch, kerosene or propane heater, charcoal stove or any open flame, the Red Cross warns.
Keep warming until full water pressure returns, then check the other taps in the house. If one pipe froze, others may have too.
When should I call a plumber about frozen pipes?
Call if you can't find the frozen section, can't reach it, or can't thaw it. Call straight away if a pipe has split or is leaking. Shut off the main water valve first, then call 865-321-8269.
A burst pipe is an emergency. See emergency plumber for what to do while you wait.
Frequently asked questions
Should I drip my faucets in Knoxville?
During a hard freeze, yes, for taps on exposed pipes or exterior walls. The Red Cross recommends letting cold water drip from taps served by exposed pipes.
What temperature should I leave the heat on if I'm away?
No lower than 55°F, according to the American Red Cross.
Updated 2026-10-07