A burst pipe is one of the most common winter emergencies in Ontario homes. When the temperature drops well below freezing, water trapped in a pipe turns to ice, expands and builds pressure until the pipe splits. The worst part is that you often do not find out until the ice thaws and water starts pouring out, sometimes inside a wall or ceiling where you cannot see it.
This guide explains why pipes burst, the emergency steps to take the moment you find one, what not to do, and how a professional crew dries your home so a single split pipe does not turn into a rebuild.
Why pipes burst in an Ontario winter
Pipes do not usually burst at the spot where they freeze. Ice forms in one section and pushes water toward a closed tap or valve. Pressure builds in the stretch of pipe between the ice and the fixture, and that is where the pipe gives way. That is why a crack can show up far from the coldest spot.
The pipes most at risk in Ontario homes are:
- Pipes running through exterior walls, especially in older homes with little insulation
- Pipes in unheated spaces such as garages, crawlspaces, attics and cold cellars
- Outdoor hose bibs that were not shut off and drained in the fall
- Kitchen and bathroom sink lines inside cabinets on outside walls
- Plumbing in cottages, rentals and homes left empty during a cold snap
Risk climbs fast during long stretches of deep cold, the kind that hits the GTA, Hamilton, Niagara, Kitchener-Waterloo and London several times each winter, and when a strong wind pulls heat out of a wall.
Warning signs of a frozen pipe
If you catch a frozen pipe before it splits, you can often avoid damage completely. Watch for:
- A tap that gives only a trickle, or nothing at all, on a very cold morning
- Frost on an exposed pipe
- A strange smell from a drain, since the gases have nowhere to go
- Bulging, damp or cold spots on a wall or ceiling near plumbing
- Gurgling or banging sounds when you open a tap
If you suspect a frozen pipe that has not burst, open the tap it feeds so water can flow once it thaws, then warm the area gently with a hair dryer, a space heater kept at a safe distance, or by opening cabinet doors to let warm air in. Never use an open flame.
Step 1: Shut off the main water valve
This is the most important step, and every adult in the home should know where the valve is. In most Ontario houses the main shut-off sits in the basement or utility room, close to where the water line comes through the front foundation wall, usually next to the water meter. Turn it clockwise until it stops.
In a condo or townhouse, the shut-off may be under a sink, behind an access panel or in a mechanical closet. If you cannot find it or it will not turn, call your building’s management or superintendent right away. As a last resort, your municipality can shut the water off at the curb stop outside.
Once the main is closed, open the lowest tap in the house, often a basement laundry tub, to drain the pressure out of the lines.
Step 2: Make the area safe
Water and electricity do not mix. If water is near outlets, a power bar, a furnace or the electrical panel, or if it is coming through a ceiling light fixture, stay out of the wet area. Turn off power to the affected circuits only if you can reach the panel while standing on a dry floor. If you cannot, call an electrician or your utility.
Watch for sagging ceilings. A bulge in drywall means water is pooling above it, and it can come down without warning. Keep people and pets away from anything that looks heavy or soft.
Step 3: Find the break and stop the spread
With the main off, the flow will slow and stop. Now look for where it came from: an exposed pipe, a wet ceiling, a stain spreading across a wall, or water pooling at a baseboard. Put buckets under drips and soak up standing water with towels or a wet vac where it is safe to do so.
Move rugs, furniture, electronics and boxes out of the wet area and onto a dry floor. Put aluminum foil or plastic under furniture legs that cannot be moved so the wood does not stain the carpet. If a lot of belongings are soaked, a professional contents pack-out can move, clean and store them while the home dries.
Step 4: Document everything for insurance
Before you clean up, take clear photos and video of the split pipe, the wet areas, damaged belongings and any ceiling or wall stains. Note the time you found the leak and when you shut the water off. Keep damaged items until your adjuster has seen them or tells you they can go.
Call your insurer as soon as you can. Most Ontario home policies cover sudden and accidental water damage from a burst pipe, but many policies limit coverage for freezing if the home was left unheated or unattended for a period of time. Read your policy or ask your broker what applies to you. For help with the paperwork, see how we handle insurance claims.
What not to do
- Do not use a torch, propane heater or any open flame to thaw a pipe. It is a fire risk and can crack the pipe further.
- Do not turn the main back on until the pipe is repaired.
- Do not walk into a flooded basement if the power may still be on.
- Do not use a regular household vacuum on water.
- Do not assume that a wall that feels dry on the surface is dry inside. Water hides behind drywall and under flooring.
- Do not wait days to start drying. The longer materials stay wet, the higher the risk of mould.
Step 5: Call a plumber and a restoration company
A plumber fixes the pipe. A restoration company deals with everything the water touched. You usually need both, and the sooner the drying starts, the less has to be torn out.
When our crew arrives for burst pipe water damage, we:
- Extract standing water with truck-mounted or portable equipment
- Use moisture meters and thermal cameras to find water inside walls, ceilings and subfloors
- Remove only the materials that cannot be saved, such as soaked carpet pad or swollen baseboards
- Set up commercial dehumidifiers and air movers to dry the structure
- Check moisture readings every day until materials are back to normal dry levels
- Document the drying for your insurance company
If the water reached the lower level, our basement flooding cleanup process covers extraction, drying and cleaning of finished and unfinished basements. You can read more about our full water damage restoration service as well.
After the leak: stopping mould before it starts
Mould can begin to grow on wet drywall, wood and carpet within 24 to 48 hours. Winter does not slow it down indoors, because your furnace keeps the house warm. That is why fast, measured drying matters so much. Our guide on how to prevent mould after water damage explains what to watch for in the weeks after a leak. If you already see growth or smell mustiness, our mould remediation team can help.
How to prevent burst pipes next winter
- Shut off and drain outdoor hose bibs before the first hard frost, and leave the outside tap open.
- Insulate pipes in garages, crawlspaces, attics and along exterior walls with foam pipe sleeves.
- Seal gaps where cold air gets in near pipes, such as around dryer vents, cable lines and rim joists.
- Keep the heat at 17°C or higher, even when you are away.
- During a deep freeze, open cabinet doors under sinks on outside walls and let a cold tap drip slowly.
- If you leave for more than a few days, ask someone to check the house, or shut off the main and drain the lines.
- Consider a smart leak detector or an automatic shut-off valve near the water heater and washing machine.
For the first day after any kind of leak, our step-by-step guide to your first 24 hours after water damage is a good checklist to keep on hand.
Frequently asked questions
At what temperature do pipes freeze in Ontario?
Pipes in unheated or poorly insulated spaces can start to freeze once outdoor temperatures stay around minus 6°C to minus 7°C or colder for several hours. Wind chill and how exposed the pipe is matter as much as the temperature itself.
Does home insurance cover a burst pipe?
Most Ontario home policies cover sudden water damage from a burst pipe. Coverage for freezing may be limited if the home was left without heat or unchecked for a set number of days. The pipe repair itself is sometimes treated differently from the damage the water caused, so ask your broker.
How long does it take to dry a home after a burst pipe?
Most homes are dry in three to five days with professional equipment once the pipe is fixed and the water is extracted. Hardwood, plaster, concrete and large losses can take longer.
Can I dry it myself with fans?
Household fans move air, but they do not remove moisture from inside walls or under flooring. Without dehumidifiers and moisture readings, a wall can look dry while still being wet enough to grow mould behind the paint.
Should I call a plumber or a restoration company first?
Shut off the main water first, then call both. A plumber repairs the pipe, and a restoration crew starts drying right away. We can work alongside your plumber so no time is lost.
Burst pipe? Call now, day or night
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