Frozen Pipes: How to Thaw Them Safely and Stop Them Freezing Again

How to tell a pipe is frozen (and roughly where)

Winnipeg's test is the quickest way to narrow it down: turn on every faucet in the house and compare.

• Low or no flow at one faucet points to a freeze in the pipe feeding that faucet, usually one that runs along an exterior wall.
• Low flow at every faucet suggests the freeze is near the water meter or where the service pipe comes in through the foundation.
• Look for frost or ice on exposed pipe, and check the cold spots first: basements, crawlspaces, garages, and cupboards on outside walls.

If a pipe has already burst

Water on the floor, a bulging or split pipe, or the sound of running water when nothing is on means you are past thawing. Toronto's first instruction is to turn off the main water supply if you can. Then call a licensed plumber, and call your insurer to start a claim. This is why every adult in the house should already know where the main shut-off valve is, and that it actually turns.

How to thaw a frozen pipe safely

Both cities give the same core method: open a tap so melting water has somewhere to go, then apply gentle heat to the frozen section. Winnipeg puts it simply: the key is slow, even heat.

1. Open the cold tap nearest the frozen section. If you don't know where the freeze is, Toronto suggests the basement cold tap, ideally in the laundry room. Running water helps melt the rest of the ice.
2. Wrap the pipe in warm towels, starting near the faucet and working back toward the coldest section (Winnipeg's method). Re-warm the towels as they cool.
3. Keep the tap running until full pressure returns. Both cities say thawing can take one to six hours depending on the weather and how much of the pipe is frozen.
4. Check the pipe for leaks once water flows. A pipe can split while frozen and only leak after it thaws. If it leaks, shut off the main and call a licensed plumber.

Hair dryers and heating pads: the two cities disagree here. Toronto lists a heating pad or hair dryer as acceptable as long as you never leave it unattended. Winnipeg advises against hair dryers and portable heaters because they are fire hazards. Warm towels are the option both cities accept. If you do use a hair dryer, stay with it, plug it into a GFCI outlet, and don't use it where water is pooling. Keep the dryer and its cord away from any water.

Never use:

• A blowtorch, propane heater, or any open flame. Toronto calls these fire and carbon monoxide hazards, and a torch can ignite the framing behind the pipe.
• Boiling water. Winnipeg warns it can cause the pipe to burst.

If you've thawed what you can reach and still have no water, the freeze is probably underground or inside a wall. That is the point to call a plumber or your municipality, not to add more heat.

Your pipe or the city's? Who to call

In most Canadian cities the water service is split at the property line. In Toronto, the City is responsible from the watermain to the property line, and the owner (or landlord) is responsible from the property line into the house.

• Toronto: call 311 and staff will investigate. If the freeze is on private property, they'll tell you to contact a plumber.
• Winnipeg: call 311 to request thawing of underground pipes. You sign an authorization form first, thawing on the City's portion is free, and you pay the fees if the freeze is on your portion.
• Everywhere else: search your municipality's name plus "frozen pipes". Responsibility, fees, and whether the city thaws private lines at all vary from place to place.
• Renting? Report the lack of water to your landlord or property manager. Toronto's advice is to find out ahead of time who handles plumbing and shut-off valves, and who to call after hours.

How to stop pipes freezing in the first place

Most of these are fall jobs (they're on our winter home prep guide), but several are things to do on the coldest nights of the year.

• Keep spaces with water pipes above 8°C, especially the area around the water meter (Toronto's figure).
• Insulate exposed pipes in basements, crawlspaces, garages, and attics with foam pipe covers.
• Seal drafts around windows, doors, vents, and anywhere wiring or pipes pass through an outside wall. A cold draft blowing on a pipe is often what freezes it.
• Disconnect outdoor hoses, shut off the outdoor water supply if it has its own valve, and open the outdoor taps to drain what's left.
• Open cabinet doors under kitchen, bathroom, and laundry sinks so warm room air reaches the plumbing.
• Keep the garage door closed if water pipes run through the garage.
• Don't turn the heat down overnight in a cold snap. Toronto suggests raising the thermostat a degree or two at night instead, if you control it.
• Run a pencil-thin stream from a vulnerable tap when overnight temperatures drop below −15°C (Toronto's threshold). You pay for the water, so keep it thin, and make sure the drain is clear.

If the same pipe freezes every winter, Toronto's advice is to ask a plumber, since the fix may be rerouting or insulating that run. For a stretch you can't easily insulate, a plug-in pipe heat cable is one option; we cover one in our winter home prep products guide. A smart water leak sensor near the hot water tank or main shut-off won't stop a freeze, but it can tell you about a burst before it floods the basement.

Going away in winter: heat, water, and insurance

This is where a frozen pipe turns from an annoying morning into a denied claim. The Insurance Bureau of Canada's guidance:

• Leave the heat on if you travel in the heating season, even for a few days. IBC says failing to do so can affect your coverage.
• Have someone check the house. Your policy sets how often a competent person has to look in to confirm the heat is still on. Read that clause before you leave, not after.
• Standard home policies generally cover damage from frozen and burst pipes only when the pipes are in the heated part of the home and reasonable steps were taken to keep the heat on.
• Vacant homes are different. IBC warns that most policies exclude frozen pipe and water damage when a home is vacant, even with permission for vacancy. If the home will sit empty, IBC's advice is to shut off the water supply and drain the lines.

These points come from IBC's winter safety page and its January 2026 winter storm release. Wording differs between insurers, so your own policy is the document that counts. Keep a copy, and your insurer's claims number, somewhere you can reach when the power is out.