Frozen Pipes in Toronto: How To Prevent and Thaw Them

A frozen pipe is quiet. Water inside it turns to ice, expands, and puts pressure on the pipe wall until something gives. Often the split itself makes no sound and releases nothing, because the ice is still plugging the hole. The flooding starts hours or days later when the ice melts and a pressurized supply line begins emptying into a wall cavity, a ceiling, or a basement.

That delay is why frozen pipes catch people out. The cold snap passes, the house warms up, and the damage arrives after everyone has stopped worrying about it. It is also why a pipe that has thawed on its own is not automatically fine.

Rosehill Restoration Services handles burst pipe water damage across the Greater Toronto Area. This guide covers the part that comes before us: keeping pipes from freezing, catching one early, and thawing it without starting a fire or making the split worse.

Freezing is about exposure, not just outdoor temperature. A pipe in a heated interior wall can sit through a hard cold snap untouched while one a few metres away splits, because the second one runs through a space the furnace never reaches or sits against cold sheathing with nothing between.

The City of Toronto points to two locations in particular: pipes running against exterior walls, and the point where the water service pipe enters the home through the foundation wall. Add to that the unheated and half heated spaces most GTA houses have somewhere.

Most of this is a single afternoon of work in October or November, and it is far cheaper than the alternative. The steps below follow the City of Toronto's frozen pipe guidance.

This trips people up when they call for help. Your water service pipe has two owners. The City owns the length running from the watermain in the street to your property line. You own the length running from the property line into the home.

That split decides who fixes what. If the freeze is on the City's section, the City handles it. If it is on your side of the property line, which includes everything inside the house, it is yours, and the City will tell you to call a licensed plumber.

When the forecast turns hard, a few temporary habits carry a house through. None of them are elegant and all of them are cheaper than a restoration bill.

The clearest sign is the simplest one. You turn on a tap during or just after a cold stretch and get nothing, or a trickle that dies. If one fixture has no water while the rest of the house is fine, the problem is usually in the run feeding that fixture.

If no fixture in the house has water, the freeze is more likely at or before the service entry, which is the point where the City and homeowner sections meet and where a 311 call makes sense.

If you can reach the frozen section and it has not split, you can often thaw it yourself. Work slowly and start at the tap end, not the middle, so meltwater and steam have somewhere to escape rather than building pressure behind the ice.

Open the affected tap first and leave it open. Running water through the thawing section helps melt the remaining ice, and an open tap tells you the moment flow returns.

Shut the water off at the main valve first, before anything else, then open the lowest tap in the house to drain the remaining pressure out of the system. If water is near electrical panels, outlets or fixtures, stay out of the area and shut off power to it at the breaker only if you can do so from a dry position. Otherwise call an electrician or the utility.

Then call a plumber for the pipe and a restoration contractor for what the water reached. Those are two different jobs. A plumber repairs the split; the water that ran through the floor and into the wall cavity is a drying problem, and leaving it is what turns a plumbing repair into a mould remediation.

Our guide on the first 24 hours after a basement flood covers the immediate sequence in more detail, and how long mould takes to grow after water damage explains why the clock matters so much.

Sudden and accidental escape of water from a burst pipe is one of the more commonly covered causes of water damage on Ontario home policies, though every policy differs and coverage turns on the specific wording and the circumstances.

Where claims run into trouble is the maintenance question. Insurers may ask whether the home was heated, whether the property was occupied, and how long the water ran before it was found. Many policies carry conditions about unoccupied homes in winter, such as requiring the heat be maintained or the plumbing drained, and about how often a vacant property is checked.

We cover the coverage question in full in does home insurance cover water damage in Ontario. The short version for winter: read your policy's unoccupancy clause before you travel, not after.

Frozen pipes are one of two predictable seasonal water damage patterns in the GTA. The other arrives in summer, when intense downpours overwhelm drainage and back water up into basements. Both reward preparation done well before the season rather than during it.

If you are working through a property checklist, our guide on preparing your GTA home for storm season is the warm weather counterpart to this one. Between them they cover most of what puts water where it should not be in a GTA home.