Seasonal
The winter pipe-freeze checklist
The short version
Disconnect hoses, drain the outdoor spigots, insulate exposed pipe, and seal the drafts that let cold air reach it. Keep the heat on, open cabinet doors on cold nights, and know where the main shutoff is. If a pipe bursts, shut the water off first, then call a plumber.
The first hard freeze rarely announces itself. The forecast slides from frost to twenty degrees, the wind picks up, and a line in the crawlspace or the wall behind the kitchen sink starts to cool. Water does not need to boil to cause trouble. It only needs to freeze, expand, and split a pipe or push a joint apart. The leak often waits until the thaw, when the ice turns back to water and finds the path into the house.
The prevention work is mostly boring, and it happens before the cold arrives. A few hours in the fall beat a frantic call in January.
Before the first freeze
Work through this list once, then again when the first cold snap is in the forecast.
| Task | Why it matters |
|---|---|
| Find and tag the main shutoff | You will not want to search for it while water is running down a wall |
| Disconnect hoses and drain the outdoor spigots | A hose traps water in the bib and the pipe behind it |
| Insulate exposed pipe in the attic, crawlspace, and garage | Those spaces run cold and often hold the first freeze |
| Seal gaps around pipes, vents, and the sill plate | A pencil-sized draft can freeze a line on a cold night |
| Service the heating system and change the filter | A house that stays warm is a house whose pipes stay above freezing |
| Blow out the irrigation system | Sprinkler lines and valves are shallow and freeze early |
| Learn which walls have plumbing | You cannot protect a line you do not know about |
| Set the thermostat and leave it on | A cold house is the setup for a burst |
| Check the crawlspace vents and access door | Cold air should not blow directly across the pipes |
| Clean the gutters before the snow | Ice dams and overflow are their own winter problem |
The shutoff is the most important item
Find the main valve now, before you need it. Open and close it once so you know it turns, then tag it with a note that says what it does. If the valve is stiff or will not close all the way, have it repaired before winter. A shutoff that fails is almost as bad as no shutoff.
Show everyone where it is. If a pipe bursts while you are at work, the person at home should not have to guess.
Insulate the pipe, but also the draft
Pipe insulation slows heat loss. It does not create heat. A line in an attic or crawlspace still needs the space around it to stay above freezing, which means air sealing and, in some cases, a heat source or a different pipe route.
Look for the places where cold air enters: the rim joist, the sill plate, holes for cable and plumbing, dryer vents, and the gap around an outdoor faucet. Seal those first. Then insulate the pipe. The order matters.
The pipes that freeze first
| Location | Why it is vulnerable | What to do |
|---|---|---|
| Outdoor hose bib | Sits outside the insulation line | Disconnect the hose, shut the interior valve, drain the bib |
| Kitchen or bath sink on an exterior wall | Little room for insulation behind the cabinet | Open cabinet doors in cold weather, add insulation if possible |
| Attic supply lines | Cold roof space, often above the insulation | Insulate and air-seal; reroute if the run is exposed |
| Crawlspace lines | Cold air, damp ground, poor access | Insulate, seal vents and the access door, keep the space dry |
| Garage wall | Unheated garage on the other side | Keep the garage door closed and insulate the wall |
| Basement rim joist | Cold corner where the floor meets the foundation | Insulate and air-seal the rim |
| Well line or pressure tank | Shallow line or an unheated pump house | Heat the space safely and check it during cold snaps |
| Irrigation and pool lines | Shallow, outdoor, and full of water | Blow out or drain before the first freeze |
| Fire sprinkler lines | Often in attics or unheated spaces | Do not drain or shut off without a professional |
When the forecast drops
A night or two of cold is easier to handle than a week, but the same habits apply.
- Open the cabinet doors under sinks on exterior walls so warm room air reaches the pipes.
- Let a trickle run from the faucet farthest from the main. Moving water freezes more slowly than still water.
- Keep the thermostat at the same temperature day and night. Turning it down to save energy can put a line at risk.
- Close the garage door and keep it closed.
- Open interior doors so warm air can move through the house.
- Check the crawlspace and any unheated addition during the coldest hours.
- If you use a space heater, plug it directly into a wall outlet, keep it clear of curtains and furniture, and never leave it running unattended. Do not use the oven or a grill to heat the house.
A trickle is an extra step, not a substitute for insulation and heat.
If you are already in it
The desk is open 7am–10pm ET, seven days a week. Call (877) 454-8068 and describe what is happening. The call is free; the independent professional sets their own charges.
If you leave for a winter trip
Do not turn the heat off. Set it low enough to save energy but high enough to keep the house safely above freezing, and ask someone to check the house during a cold snap. A thermostat that can be monitored remotely is useful, but it does not replace a person who can open a door if something fails.
If the house will be empty for a long stretch, consider shutting off the main water valve and draining the lines. Turn off the water heater if the power or fuel will be off, and follow the manufacturer's instructions. Do not drain a fire sprinkler system yourself; that is a job for a professional.
Leave the cabinet doors open and the interior doors open before you go. A closed-up house with the heat off is the classic setup for a burst that nobody discovers until the floors cup.
If a pipe freezes
The first sign is often a faucet that slows to nothing while the rest of the house still has water. You may hear a knock or a hiss in the wall, see frost on a visible pipe, or notice a bulge. Do not assume the line is fine because no water is leaking yet. The split may open when it thaws.
Leave the faucet open so melting water has somewhere to go. Find the frozen section by feel and by following the line from the fixture back toward the supply. Warm it gently with a hair dryer, a heat gun kept moving on low, or towels soaked in warm water. Work from the faucet end toward the freeze.
Never use an open flame, a charcoal grill, or a blowtorch on a pipe. Never pour boiling water on a toilet or a PVC line. If the pipe is inside a wall or you cannot find the freeze, call a plumber rather than opening the wall at random.
Watch for water as it thaws. A pipe that has already split will leak once the ice melts, sometimes inside the cavity rather than at the fixture.
If a pipe bursts
Start with the first ten minutes of a water leak: shut off the main valve. If you cannot reach it, call a plumber and say that the water is running and the shutoff is inaccessible. Open the nearest faucets to drain the remaining water and take pressure off the system.
If water is near an outlet, a panel, or a light fixture, do not touch the electrical parts. Shut off the circuit at the panel only if you can stand on a dry floor and reach it safely. If you see sparking, smoke, or smell burning, get out and call 911 or the utility.
Move furniture and valuables away from the water, then call a plumber and a water-damage crew. Take photos before anything is moved. A burst line can release a lot of water in a short time, and the drying matters as much as the repair.
After the thaw
Open the faucets one at a time and check for leaks at the fixture, the supply lines, and the shutoff. Look under the sink, in the basement, and in the crawlspace. If the water meter keeps moving with every fixture closed, something is still leaking.
Check the ceilings and walls along exterior walls for stains that were not there before. Water from a split pipe can travel along a joist and show up far from the repair. If the house was wet, a restoration crew can check the moisture with a meter rather than waiting for the smell.
The bottom line
Keep the water out of the outdoor lines, keep the heat on, and seal the drafts that let cold air reach the pipe. Know where the shutoff is and show someone else. If a line freezes, warm it slowly and leave the faucet open. If it bursts, shut the water off first and worry about the repair second. The house can be dried; a line that runs for hours leaves the mark.