Frozen and burst pipes: questions and answers
Direct answers about frozen and burst pipes in Ontario winters.
Call 24/7: (416) 938-455221 questions people search for, each answered in a few sentences. Where there is more to say, the answer links to the full guide.
What temperature do pipes freeze and burst at?
Water freezes at 0 degrees Celsius, but pipes inside a building are usually at risk when the outdoor temperature falls to about minus 6 or lower for several hours, depending on insulation, wind and where the pipe runs.
Will pipes burst at 0 degrees Celsius (32 Fahrenheit)?
Rarely. At the freezing point, pipes inside a heated house are protected by the warmth around them. The risk rises as it gets colder, and for pipes in unheated spaces or outside walls.
How long does it take for pipes to freeze?
In severe cold, an exposed pipe in an unheated space can freeze within a few hours. A house that loses heat entirely usually takes a day or more to cool enough for pipes to freeze, less if it is poorly insulated.
How do I know if my pipes are frozen? What are the signs?
A tap that produces a trickle or nothing in very cold weather, frost on an exposed pipe, a bulge in the pipe, or odd smells from a drain. One dead tap while others work points to that branch.
What do frozen or burst pipes sound like?
Frozen pipes may bang, clank or gurgle as ice shifts and water is forced past. A burst pipe sounds like hissing or rushing water inside a wall or ceiling, often with dripping.
Do frozen pipes thaw on their own? Will they fix themselves?
They thaw when it warms up, but that is when a split pipe starts to leak. Shut off the water, open the tap and thaw the pipe gently, so that you are there when it thaws.
Can frozen pipes thaw without bursting?
Often, yes. Many frozen pipes thaw with no damage. The danger is that you cannot tell whether a pipe has split until water flows again, so keep the main valve within reach.
Do pipes burst when they freeze or when they thaw?
The pipe splits when it freezes, from the pressure trapped between the ice and a closed tap. The leak appears when it thaws and water can flow through the split.
Why do pipes burst when they freeze?
Water expands as it turns to ice. The ice blocks the pipe and pressure builds in the water trapped between the blockage and the closed tap until the pipe or a fitting gives way.
Can pipes be partially frozen?
Yes. A partial blockage gives reduced flow. Treat it the same way: open the tap, warm the pipe gently and keep watching it.
How long can pipes stay frozen?
As long as the cold lasts. The longer they stay frozen, the more likely a split, and the more ice has formed along the line. Do not wait for the weather to change.
Can I flush the toilet if the pipes are frozen?
Once, if the tank is full. It will not refill if the supply is frozen. If the drain may be frozen too, do not flush, because the water has nowhere to go.
Can pipes burst in warm weather or in summer?
Yes. Pipes also fail from corrosion, worn fittings, high water pressure, water hammer and physical damage. Freezing is the winter cause, not the only one.
What causes burst pipes? How common are they?
Freezing, corrosion, failed joints and fittings, high pressure and age. Burst and leaking pipes are among the most common sources of home insurance water claims in Canada.
What is the difference between a burst pipe and a leaking pipe?
A burst is a sudden failure releasing a large flow. A leak is slow. The distinction matters for insurance: sudden bursts are commonly covered, while slow leaks over time usually are not.
Is a burst pipe or a frozen pipe an emergency?
A burst pipe is: shut off the main valve at once. A frozen pipe is urgent, because it may already have split. Shut off the water to it and thaw it carefully.
Can burst or frozen pipes be repaired? Who fixes them?
Yes. A plumber cuts out the damaged section and replaces it, and can thaw pipes safely. A restoration company deals with the water damage.
How do I prevent frozen and burst pipes?
Keep the heat on, insulate pipes in cold areas, seal draughts, open cabinet doors under sinks on outside walls in extreme cold, shut off and drain outdoor taps, and shut off the main when away.
How much should a tap drip to prevent freezing?
A thin, steady trickle from the tap served by the vulnerable pipe is enough. Moving water is slower to freeze and relieves pressure. It is a short-term measure for extreme cold, not a substitute for insulation.
Who is responsible for a burst pipe in an apartment or condo?
In a rental, the landlord repairs the building. In a condo, the corporation generally repairs common pipes and the building to the standard unit, and the unit owner their improvements. Tenants and owners insure their own belongings.
How do I report a burst water main?
Call your municipality. In Toronto that is 311. A burst inside your property is your responsibility: shut off your main valve and call a plumber.
Need this dealt with? See burst pipe water damage.
Damage does not wait for business hours. Neither do we.
Call any time. If you would prefer we call you, request a callback.