What temperature do pipes freeze at? Water freezes at 32°F, but pipes inside a heated house rarely freeze until it is much colder outside. Research from the University of Illinois found that pipes in unheated spaces like crawl spaces, attics, garages, and exterior walls are at risk once the outdoor temperature falls to about 20°F. Treat a forecast in the teens as the night to protect them.
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Water left in an outdoor line is the most common winter pipe failure, and the easiest to prevent. Do this before the first night below freezing.Shut down the outdoor water
Disconnect every garden hose
A hose left on the spigot traps water in the valve, where it freezes and splits the pipe just inside the wall. Even frost-free spigots burst this way, because the water has nowhere to drain. Drain the hoses and store them inside.If you skip it: The split happens inside the wall, so the first sign is often a wet basement the first time someone turns on the spigot in spring.Shut off and drain each outdoor faucet
Each outdoor faucet usually has its own shutoff valve inside the house, in the basement or crawl space right behind where the faucet comes through the wall. Turn it off, then open the outdoor faucet to let the line drain and leave it open for the winter. Frost-free faucets don’t need the inside valve closed, but the hose still has to come off. An insulated cover adds insurance on an exposed wall.Blow out the sprinkler system
Shut off the irrigation supply and clear the water out of the lines, either through the system’s drain valves or by blowing the zones out with compressed air. Blowouts need a compressor with enough volume and a pressure the pipes can take, so most people hire it out. Book it before the first hard freeze, not after.If you skip it: Frozen water cracks the backflow preventer and the buried lines, and those repairs cost several times what the blowout does.Close the pool or hot tub
Lower the water, blow out and plug the lines, drain the pump, filter, and heater, balance and treat the water, and cover it. A pool service can do all of it in one visit.2
The pipes that freeze run through unheated space: crawl spaces, attics, garages, and exterior walls, especially on the side of the house that faces the wind. Moving cold air freezes a pipe much faster than still cold air.Keep pipes from freezing
Insulate pipes in unheated spaces
Slip foam insulation sleeves over exposed pipes in the crawl space, attic, garage, and any unheated basement, and seal the gaps where pipes pass through exterior walls. It takes minutes per run. For a stretch that freezes every year, add a thermostat-controlled heat cable and follow its instructions exactly.Close off the cold air
Close or cover crawl space vents for the winter if yours are the kind you open in summer, keep the garage door shut when water lines run through the garage, and seal drafts around pipes where they enter the house.On the coldest nights, open the cabinets and let a faucet drip
Open the sink cabinets on exterior walls so room heat reaches the pipes, and let the faucet farthest from where water enters the house drip slowly, hot and cold. Moving water is harder to freeze, and an open faucet relieves the pressure that actually bursts a frozen pipe. Keep the thermostat at the same setting day and night during a cold snap.3
The heating system keeps every pipe in the house above freezing, so it belongs on this list. Book service early: technicians fill up once the first cold week arrives.Get the heat ready
Service the furnace or boiler and change the filter
Have the heating system checked before you need it every day, and put in a fresh filter. Write the date on the filter’s edge so you know when it went in.How long does an HVAC system last?Test the carbon monoxide and smoke detectors
Heating season is carbon monoxide season. Test every detector, replace batteries, and check the date printed on the back, because detectors expire.How long do smoke detectors last?Have the chimney inspected before the first fire
A yearly inspection catches creosote buildup and cracked flue liners before they start a chimney fire. Have it swept if the inspector finds buildup, and make sure the damper opens and closes.Clean the gutters after the leaves drop
Wait until the trees are bare, then clear the gutters and make sure the downspouts carry water well away from the foundation. Clogged gutters hold water that freezes into ice dams at the roof edge.If you skip it: Ice dams push meltwater under the shingles and into the ceilings and walls below.How long do gutters last?Seal drafts around doors and windows
Replace worn weatherstripping and recaulk gaps around window and door trim. It keeps heat in, and keeps cold air off the pipes that run through exterior walls.4
A week away over the holidays, a vacation home, and a house on the market all need a plan, because nobody is there to notice the furnace quit.Leaving the house empty
Keep the heat at 55°F or higher
Set the thermostat no lower than 55°F, put fresh batteries in it, and leave interior doors and the sink cabinets on exterior walls open so heat reaches the pipes. It costs far less than a thaw.Turn off the main water for longer trips
For anything longer than a few days, shut off the main water valve and open a faucet on the lowest floor to drain the lines. With the water off, a failure can only release what is left in the pipes instead of running until you come home. Set the water heater to its vacation setting.How to shut off your water, gas, and electricityFully winterize a house that will sit unheated
If the heat will be off, the plumbing has to be emptied completely: water off at the main, water heater off and drained, every line drained or blown out, and nontoxic RV antifreeze poured into drain traps and toilets. This is worth hiring a plumber for. Standard homeowners policies typically cover freeze damage only if you kept the heat on or shut off and drained the water, so read yours before you leave.Have someone check on the house
A neighbor who walks through every few days catches a failed furnace before the pipes do. A leak and temperature sensor that alerts your phone is the next best thing.5
Move fast, and never use an open flame on a pipe.If a pipe freezes or bursts
If a faucet only trickles, thaw the pipe
A trickle on a cold morning means ice somewhere in the line. Leave the faucet open and warm the pipe starting at the faucet end and working back toward the cold section, using a hair dryer, a heating pad, or a space heater kept at a safe distance. Never use a torch or a propane heater. If you can’t find or reach the frozen section, call a plumber.If a pipe bursts, shut off the main water valve
Turn off the main shutoff, then open a faucet on the lowest floor to drain the lines. If water is near outlets or the electrical panel, switch off the power only if you can reach the panel from a dry spot; otherwise call the electric utility. Photograph the damage before you clean up, then call a plumber and your insurer.How to shut off your water, gas, and electricity6
Landlords usually handle the heating system and the plumbing, but tenants usually control the thermostat, and a frozen pipe can still be your problem.