Frozen pipes in Canada: what to do before a pipe bursts
Practical steps for a suspected frozen pipe, including what not to do, when to shut off water and when to call a plumber.
Updated September 28, 2026First: know where the water shutoff is
A frozen pipe can split before or during thawing. Knowing how to shut off the main water supply matters because a crack may only become obvious once flow returns.
Do not use an open flame
Both Toronto and Ottawa explicitly warn against using an open flame to thaw frozen plumbing. Open-flame methods create a fire hazard and can damage surrounding materials.
- Avoid torches and open flames
- Keep electrical heating devices away from water
- If a pipe is bulging, cracked or leaking, treat it as a burst-pipe problem rather than a simple thaw
When to call a plumber
If you cannot locate the frozen section, cannot restore flow safely, suspect a split pipe or see any active leak, a plumbing request should be treated as time-sensitive.
- No water at multiple fixtures
- Visible bulging or cracking
- Water appears after thawing begins
- The frozen section is inside a wall or otherwise inaccessible