Last updated: October 17, 2026. Guidance checked against City of Toronto, Region of Peel, Insurance Bureau of Canada and Canadian Red Cross advice on that date.
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Key takeaways
– Pipes freeze where cold air reaches them: along outside walls, in crawl spaces, garages and attics, and where the water service enters through the foundation.
– The best prevention is boring: seal air leaks, insulate exposed pipes, shut off and drain outdoor taps, and keep the house heated. The Region of Peel says to keep your home no lower than 15°C.
– In Toronto, when nighttime temperatures are forecast below −10°C, the City asks residents with pipes prone to freezing to run a pencil-thin stream of cold water.
– Heat cable works for problem sections, but use one certified for use in Canada and follow the instructions exactly.
– To thaw: open a tap, warm the pipe with a hair dryer, heating pad or warm towels, and never use an open flame. Know where your main shut-off is before you start.
A frozen pipe is one of the most common and most expensive winter problems in Canadian homes. When water freezes it expands, and that can split a pipe. Often you won’t know until the ice thaws and water starts pouring into a wall or ceiling.
Most frozen pipes are preventable, and if one freezes you can usually thaw it safely yourself. Here’s what works, and when to call a plumber.
Where pipes freeze, and why
The City of Toronto says the likely places for frozen pipes are against exterior walls and where the water service pipe enters the home through the foundation wall (City of Toronto: Prevent or thaw frozen pipes). The Region of Peel adds basements, crawl spaces, and places near a cracked foundation, and notes that the water meter is often in the coldest, lowest part of the house (Region of Peel: Preventing frozen pipes).
Usually the culprit is cold air moving across the pipe: a draft at the rim joist, a dryer vent, a hose bib or an open garage door. Pipes inside insulated walls can freeze too, if the insulation is behind the pipe instead of on the cold side of it.
Common trouble spots in Canadian homes:
- supply lines to an outside tap (hose bib)
- pipes along the rim joist at the top of the foundation wall
- kitchen sinks on an exterior wall, especially with closed cabinet doors
- plumbing in an attached garage or over an unheated crawl space
- the main water line and meter where they come through the foundation
- cottage and seasonal homes left with the heat turned down
Prevention, in order of what helps most
1. Shut off and drain outdoor taps (fall)
Outdoor faucets are often the first to freeze. Toronto and Peel both say to unscrew garden hoses, turn off the outdoor water supply at the inside shut-off valve, and open the outside tap to drain it (City of Toronto; Region of Peel). Do it before the first hard frost. Leave the outside tap open over the winter so any trapped water can expand without splitting the pipe.
Even a “frost-free” hose bib can freeze and split if a hose is left attached, because the hose traps water in the valve body.
2. Seal air leaks near pipes
Toronto recommends sealing air leaks to stop cold air from getting in, checking around windows and doors, electrical wiring, dryer vents and pipes (City of Toronto). In a basement, look closely at the rim joist and where pipes, wires and vents pass through the wall. Low-expansion spray foam or caulk handles most small gaps. This also cuts your heating bill.
3. Insulate exposed pipes
Wrap foam pipe insulation around pipes most prone to freezing, especially near outside walls and in crawl spaces, attics and garages (City of Toronto). Foam sleeves are cheap and easy: measure the pipe size, slide the sleeve on, and tape the seams and joints.
Remember that insulation slows heat loss but doesn’t create heat. A pipe in an unheated space will still freeze eventually during a long cold snap if it has no heat source. That’s where heat cable comes in.
4. Keep the house warm, including at night and when you’re away
Advice varies slightly by source:
- The Region of Peel says to keep your home no lower than 15°C (60°F), and to leave cabinet doors open if your water meter is in a cabinet (Region of Peel).
- The Canadian Red Cross tips (as reported by CBC) say to keep the thermostat at the same temperature day and night and, if you go away, leave the heat set no lower than 13°C (55°F) (CBC News).
Either way, skip the deep nighttime setback during a cold snap. Open the kitchen and bathroom cabinet doors on exterior walls so warm room air can reach the pipes, and keep the door between the house and an attached garage closed.
5. The drip trick, during extreme cold
When nighttime temperatures are forecast to drop below −10°C, the City of Toronto urges residents with pipes prone to freezing to run a pencil-thin stream of water, 24 hours a day, until temperatures return to normal seasonal averages, and to keep the drain clear so it doesn’t overflow (City of Toronto news release). Moving water is much harder to freeze.
Use the tap that is fed by the vulnerable pipe, or a basement cold tap near where the service enters the house. If you’re on a private well and septic system, think about how much water you’re sending to the septic before running a tap for days.
6. Heat cable for problem sections
For a pipe that freezes every winter and can’t be rerouted or insulated from the cold side, a pipe heating cable is the usual fix. A few rules matter:
- Buy a cable certified for use in Canada (look for a recognized certification mark such as CSA or cUL) and rated for your pipe material and location, indoor or outdoor.
- Follow the manufacturer’s instructions exactly. Constant-wattage cables generally must not be overlapped or crossed; some self-regulating cables can be. Don’t cut, splice or modify a cable unless the instructions say you can.
- Ground-fault protection matters. Rule 62-116 of the Canadian Electrical Code requires ground-fault protection for heating cable sets (Guide to the CEC, Section 62). If you’re hardwiring a cable or adding a circuit, hire a licensed electrical contractor. In Ontario, electrical work generally requires a permit from the Electrical Safety Authority.
- Inspect it every fall. Replace any cable with a cracked or damaged jacket, charring, or a wet connection.
- Thermostat-controlled cables turn on only when needed, which saves power and reduces wear.
Peel also suggests protecting the pipes at your water meter with a low-wattage wrap heater, heat tape, heat cables controlled by a thermostat, or foam insulation (Region of Peel).
7. Fix the cause for good
If the same pipe freezes year after year, fix the building, not just the pipe. Insulate and air-seal the rim joist, move the pipe to the warm side of the insulation, or have a plumber reroute it. More cold-weather guides are in our Winterizing section.
Going away in winter? Read your insurance policy
The Insurance Bureau of Canada (IBC) says standard home insurance policies cover the resulting damage from frozen and burst pipes, provided the pipes are in the heated portion of your home and reasonable steps are taken to maintain heat. Most policies spell out how often your home must be checked by a competent person while you’re away, and most exclude frozen-pipe water damage if the home is vacant. If a home will be vacant, IBC says to shut off the water supply and drain the lines (IBC: Does my insurance cover damage caused by extreme cold?).
Before a winter trip:
- Check your policy’s rules on how often someone must check the house, and arrange that person.
- Keep the heat on and tell your house-checker how to find the main water shut-off.
- Consider a water leak alarm or a smart temperature sensor that alerts your phone.
- For a long absence or a seasonal property, shut off the water and drain the lines.
How to tell if a pipe is frozen
The City of Toronto says that if you turn on your taps and have no water, the pipes in your home may be frozen (City of Toronto). Other clues: only a trickle comes out, one fixture works while another doesn’t, or you can see frost on a section of pipe. Check other taps too. If one pipe has frozen, others nearby may have as well.
How to thaw a frozen pipe safely
- Find your main shut-off valve first. It’s usually in the basement where the water pipe comes through the foundation. If the pipe has split, water will start flowing as it thaws, and you’ll need to shut it off fast.
- Open a tap. Toronto recommends a basement tap, preferably the cold-water laundry faucet (City of Toronto). Moving water helps melt the ice and tells you when the pipe has cleared.
- Apply gentle heat to the suspected frozen section, working from the tap end back toward the frozen area. Use an electric heating pad, hair dryer, space heater or warm towel or rag. Don’t leave electrical devices unattended.
- Be patient. Toronto says thawing can take between one and six hours, depending on the outside temperature and how much of the pipe is frozen.
- Turn the water back on slowly once flow returns, and check for cracks and leaks.
What not to do: don’t use a torch or any open flame, kerosene or propane heater, or charcoal stove to thaw a pipe. It’s a fire hazard, and it can damage the pipe (City of Toronto). Keep space heaters away from anything flammable, and never use electrical tools while standing in water.
When to call a plumber or the city
Call a licensed plumber if you can’t find or reach the frozen section, the pipe won’t thaw, or it has burst. In Toronto, if the steps above don’t solve the problem, you can call 311; if City staff find that the frozen pipe is on private property, you’ll be advised to contact a plumber (City of Toronto: No water or low water pressure). Outside Toronto, check your own municipality’s water department.
If a pipe has burst, shut off the main valve, turn off electricity to any area where water reaches outlets or appliances (only if you can do it from a dry spot), call a plumber, and call your insurer. IBC notes that most insurers have 24/7 claims reporting.
Safety note
- Never thaw pipes with an open flame. It’s a leading cause of fires during cold snaps.
- Water and electricity don’t mix. Stay out of standing water near outlets, cords or appliances.
- Keep space heaters on a stable surface, at a safe distance from anything that can burn, and don’t leave them unattended.
- Electrical work on heat cable circuits should be done by a licensed electrical contractor.
- Clear snow from furnace and water heater exhaust vents during winter storms to prevent carbon monoxide build-up, and keep working CO alarms.
FAQ
At what temperature do pipes freeze?
Water freezes at 0°C, but whether a pipe freezes depends on how cold the air around it gets and for how long, and whether there’s a draft. That’s why Toronto issues its frozen-pipe reminder when nights are forecast below −10°C.
Should I leave a tap dripping all night?
During extreme cold, if you have pipes that are prone to freezing, yes. Toronto recommends a pencil-thin stream, not just an occasional drip.
Can I use a hair dryer on PEX or plastic pipe?
Gentle heat like a hair dryer or heating pad is the method the City of Toronto recommends. Keep it moving, and never use a torch, which can melt plastic pipe.
Does home insurance cover burst pipes?
IBC says standard policies cover resulting damage if the pipes are in the heated part of the home and you took reasonable steps to keep heat on. Vacancy rules matter, so check your policy before you travel.
The bottom line
Prevent first: drain the outdoor taps in fall, seal the drafts, insulate the pipes and keep the heat on. During a deep cold snap, run a pencil-thin stream. If a pipe still freezes, open a tap, warm it gently, and never reach for a torch. And before spring, read our guide to stopping a leaking basement in spring.
This article is general information, not professional advice. See our Disclaimer.