Frozen pipe? What to do right now, and what temperature pipes freeze at
Open the dead faucet and leave it open, then warm the pipe slowly from the faucet end back toward the ice with a hair dryer, heating pad, or hot wet towels. Never use an open flame. Find your main shutoff first, because a split pipe floods the moment the ice lets go.
How do I know if a pipe is frozen?
The clearest sign is one faucet with no water on a cold morning while the rest of the house works normally. That means a plug of ice somewhere upstream of that fixture.
Other signs point to where the ice is and whether damage is already done:
| What you see | What it most likely means |
|---|---|
| One faucet dead, rest of house fine | Ice plug upstream of that fixture |
| No water anywhere after a freeze | Ice plug upstream of the whole house. Find the main first; the pipe may already be split |
| Reduced pressure everywhere after a freeze | Partial ice, or a split already leaking. Check the meter with everything off |
| Outdoor faucet frozen even though it is frost-free | A hose was left connected. Frost-free faucets only drain with the hose off |
| Water stains on a ceiling or wall | The pipe has burst. Shut off the main and call a plumber |
The pipes that freeze first are the ones with unheated air on one side: outdoor hose bibs, garage lines, crawlspace and rim joist runs, pipes in exterior walls, attic runs, and sinks on an outside wall.
How do you safely thaw a frozen pipe?
Open the affected faucet, leave it open, and warm the pipe gently from the faucet end back toward the ice. Working from the open end gives melting water and pressure somewhere to go.
- Locate your main shutoff before you start. If the pipe has already split, water arrives the moment the ice lets go.
- Open the dead faucet and keep it open the whole time.
- Apply gentle heat with a hair dryer, a heating pad, or towels soaked in hot water.
- Work slowly toward the ice and keep checking behind you for drips or spraying.
If you can't reach the frozen section, or it runs inside a finished wall, stop and call a plumber.
What should you never use to thaw a frozen pipe?
Never use an open flame. That means no blowtorch, no propane or kerosene heater, and no charcoal.
An open flame will start a fire or crack the pipe, and every safety authority gives the same advice. Slow, gentle heat is the only safe approach.
If you use a hair dryer, keep it away from any water that is already on the floor.
Where is my main water shutoff, and what do I do if a pipe bursts?
Your main shutoff is usually where the supply line enters the house. With a basement, it is almost always within three to five feet of where the line comes through the wall, usually on the side facing the street. On a slab, check near the water heater, in the garage, in a utility closet, or under the kitchen sink.
A lever handle is a ball valve: one quarter turn closes it. A round wheel is a gate valve: several turns clockwise. If a valve resists hard, stop. Forcing a seized gate valve can shear the stem and leave it stuck open.
If a pipe bursts, follow this order:
- Water off at the inside main.
- Electricity, carefully. Never step into standing water to reach the panel. If water is between you and the breakers, call the utility or an electrician to cut power at the meter.
- Drain the system. Open the lowest and highest taps and flush the toilets.
- Photograph everything before you move it, and keep wet carpet and drywall until an adjuster has seen it.
- Start drying immediately. Dry everything within 24 to 48 hours, because mold can grow on wet materials after that.
The curb stop at the property line is usually the utility's job, not yours. Know where it is, and leave it to them.
What temperature do pipes freeze at?
Pipes in unheated space, especially uninsulated ones, are at real risk of freezing once temperatures drop to around 20°F (−7°C) or below. It is sustained cold that does it, not a brief dip.
A single night at 18°F is usually survivable. Three days at 18°F is not. Wind makes it worse: air driving through a crawlspace vent or an open soffit freezes a pipe far faster than still air at the same temperature.
Mild-climate homes are often more exposed, not less. Pipes there tend to run through unheated space because nobody expected a hard freeze, so one cold snap can do more damage than a whole northern winter.
Frozen pipes often burst after the ice thaws, not while the ice is still in place. The split usually happens between the ice plug and a closed faucet, where pressure has nowhere to go. That is why a pipe can freeze on Tuesday and burst on Thursday.
How do I stop my pipes from freezing again tonight?
The evening a hard freeze is forecast, four quick moves carry you through:
- Hold one thermostat temperature day and night. A nighttime setback can drop the crawlspace below freezing.
- Open cabinet doors under sinks on exterior walls, after moving cleaners out of reach of kids and pets.
- Run one cold tap at a pencil-thin stream, usually the fixture farthest from where the water comes in.
- Keep the garage door closed, especially if laundry lines run through that wall.
For the long term, disconnect every garden hose, cover outdoor faucets, and foam-sleeve the exposed runs. Seal the air leaks too: foam slows heat loss but doesn't stop cold air pouring through a vent. If you leave town, keep the heat at no lower than 55°F (13°C), or shut off the main and drain the lines.
Doing it yourself
$30–80 for foam sleeves, hose bib covers and tape for a whole house
Calling a pro
$150–400 to insulate the exposed runs
Time to check: An afternoon.
When to stop and call a pro
- The pipe has already burst, or you find water staining a ceiling or wall.
- The frozen section is out of reach or inside a finished wall.
- You have polybutylene or galvanized pipe, which is brittle and splits easily when handled.
- The main shutoff won't turn or the stem snaps. Call the utility to shut the curb stop, then a plumber.
- There is standing water near anything electrical, or you'd have to cross water to reach the panel.
- A gas water heater or furnace has been flooded. Don't relight or run it until a qualified technician inspects it.
Want the full step-by-step?
The two $6 guides go further: How to Keep Your Pipes from Freezing (No. 25) walks the six at-risk runs, shows how to foam, air-seal and add heat cable correctly, and ends with a printable cold-snap checklist, while Find Your Main Shutoff & Burst-Pipe Plan (No. 29) covers testing your valve safely, the other shutoffs worth knowing, and a fill-in panel-door card. Both are included in the $14 Freeze-Proof Plumbing Kit.
Get “How to Keep Your Pipes from Freezing” — $6 →Get “Find Your Main Shutoff & Burst-Pipe Plan” — $6 →Or buy the guide inside the Freeze-Proof Plumbing Kit (5 guides, $14) or The Winter Home (all 20 winter guides, $39). Instant PDF, no subscription.
Frequently asked questions
Should I leave a faucet dripping when it's below freezing?
Yes, on nights a hard freeze is forecast. Run one cold tap at a pencil-thin stream, ideally the fixture served by the most exposed pipe, usually the one farthest from where water enters the house. Moving water resists freezing, and an open faucet gives pressure somewhere to go if ice does form.
What temperature should I keep my house at when I leave in winter?
Set the heat no lower than 55°F (13°C), not off and not 45°F. If you'll be gone more than a few days, shut off the main and drain the system by opening the lowest and highest faucets. Many homeowner policies set a minimum heat condition for freeze claims, often around 55°F, so check yours.
Why did my frost-free outdoor faucet freeze?
Almost always because a garden hose was left connected. A connected hose traps water in the faucet, and frost-free faucets only drain when the hose is off. Disconnecting every hose before winter is the single highest-value task in freeze prevention, and it costs nothing but thirty seconds per faucet.
Does homeowners insurance cover a frozen pipe that bursts?
Policies generally cover sudden, accidental discharge, including a pipe that bursts because it froze. A common exclusion is freeze damage in a home left unheated or unoccupied. Many require heat at a stated minimum, often 55°F, or the water shut off and drained. Terms vary, so read your own policy before winter.
How can I tell if a pipe is leaking where I can't see it?
Use the meter trick. Turn off every fixture and appliance that uses water, then find the meter and watch the small triangle, star, or dial that spins on low flow for a couple of minutes. Any movement with everything off means water is going somewhere it shouldn't, and it's time to call a plumber.
Sources
Safety guidance and key figures were checked against these outside sources on October 22, 2026. Dollar figures are typical ranges, not quotes.
- Preventing & Thawing Frozen Pipes (American Red Cross). Open faucet, gentle heat (hair dryer, heating pad, hot towels), no open flame, same thermostat day/night, cabinets open, garage door closed, 55F when away.
- Winter Storms: Preventing and Thawing Frozen Pipes (Texas A&M AgriLife Extension). Pipes at risk when outside temperature reaches about 20F or below; a frozen pipe may already be cracked and leak once thawed; shut main if so.
- Cold Weather, Frozen Pipes? Extension Gives You All You Need to Know (University of Illinois Extension). Thawing with gentle heat, open flames can make water boil and burst pipe, pipes frozen for hours may crack and leak after thaw, know the shutoff, check other faucets.
- Water Pipes (Disaster Resources) (University of Illinois Extension). Heat no lower than 55F, never thaw with open flame or torch, electric shock caution near standing water, know shutoff, insulate and open cabinets.
- Frozen pipes advice and insurance (consumer bulletin) (DC Department of Insurance, Securities and Banking). Policies generally cover sudden/accidental burst-pipe damage but may deny if reasonable precautions skipped; some require minimum heat; keep at least 55F; drain if vacant and unheated; hair dryer only, never flame.
- Mold and moisture guide: A Brief Guide to Mold, Moisture and Your Home (U.S. EPA). Dry water-damaged areas and items within 24-48 hours to prevent mold growth.
- Safety Guidelines: During & After a Winter Storm (CDC). Drip taps, open cabinet doors, thaw slowly with hair dryer, never use a torch.
- Winter Ready Home Checklist (IBHS (Insurance Institute for Business & Home Safety)). Insulate pipes in attics/crawlspaces/exterior walls, thermostat no lower than 55F, cabinets open, drip faucets, pre-2010 homes often lack frost-proof faucets.
More winter fixes
For general homeowner reference only. When a repair involves gas, major electrical, or structural work, call a licensed professional.