Winter tests every piece of plumbing in a Canadian home. From a Prairie cold snap that holds at minus 30 for a week to the freeze-thaw swings of southern Ontario and the Maritimes, cold weather finds any water that has nowhere to go. The good news is that freeze damage is one of the most preventable problems in residential plumbing. This guide covers what freezing does to pipes and fixtures, how to winterize a cottage properly, and what to check in spring.
Why freezing water damages plumbing
Water expands by roughly nine percent when it freezes. In an open bucket, that is harmless. Inside a sealed pipe or valve body, it is not. The burst does not usually happen where the ice forms; it happens between the ice plug and a closed faucet, where trapped water has no room left. That is why a pipe can freeze on Tuesday and flood the basement on Friday when it thaws, and why the failure point is so often the fixture itself: a faucet body, a supply stop or a toilet fill valve. The takeaway is simple: anywhere water can sit in an unheated space, it needs to be drained, protected or kept moving.
Outdoor taps and hose bibs
The most common freeze casualty in Canada is the humble outdoor tap. Before the first hard frost:
- Disconnect every hose. A hose left attached traps water inside the tap, where it will freeze even on a frost-free model. This one habit prevents most hose bib failures.
- Shut off and drain standard bibs. Close the interior shut-off valve, then open the outdoor tap so the exposed stub of pipe can empty.
- Know what frost-free really means. A frost-free sillcock closes the valve deep inside the heated part of the house, so the exposed section drains itself. It only works when installed with a slight downward slope and no hose attached.
- Treat insulated covers as a backstop, not a primary defence. They slow heat loss; they do not stop a deep freeze.
Garages, crawl spaces and cold corners
Plenty of homes from Vancouver to Halifax have plumbing in spaces that hover near freezing: a garage utility sink, a powder room over an unheated porch, supply lines through a crawl space. A few defences work well together. Insulate vulnerable supply runs. Leave cabinet doors open under sinks on exterior walls during cold snaps so room heat reaches the pipes. During extreme cold, let the farthest faucet run at a pencil-thin trickle overnight, because moving water freezes far less readily than still water. And if a sink lives in a space you cannot keep above freezing, treat it like a cottage fixture: shut off its supply, drain the lines and protect the trap. That applies to laundry and utility sinks in garages and unheated mudrooms just as much as anything at the lake.
Winterizing a cottage or seasonal home
Cottage country from Muskoka to the Laurentians to Manitoba's lake district empties out each fall, and the plumbing has to sit through months below zero with no heat. The sequence matters:
- Shut off the water source. Turn off the well pump or close the main, then open a low and a high faucet to break the vacuum and drain the lines.
- Drain the water heater following the manufacturer's instructions, with power or gas off first.
- Blow out the lines if you can. Low-pressure compressed air clears the water that gravity misses. Many cottagers hire this out once a year.
- Drain every toilet. Flush with the supply off, then sponge remaining water from the tank and bowl. Vitreous china is tough, but a tank full of ice will crack it.
- Protect every trap. Each fixture drain holds a small plug of water: sinks, tubs, showers, floor drains, the laundry standpipe, even the dishwasher. Pour non-toxic plumbing antifreeze (propylene glycol, sold for plumbing and RV use, never automotive antifreeze) into each one, including the toilet bowl.
- Do a slow walk-through. The forgotten fixtures are the rarely used ones: the basement shower, the bar sink, a bidet seat with its own water line.
Jetted and air-jet tubs hold residual water in their internal lines after draining, so follow the manufacturer's winterization steps; an empty tub is not always a dry tub.
How fixture materials handle the cold
Cold alone rarely hurts a quality fixture; trapped water does the damage. Here is how common materials behave:
| Material | Cold-weather behaviour | What actually fails |
|---|---|---|
| Vitreous china (toilets, basins) | Unaffected when dry, even in a deep freeze | Water frozen in the tank, bowl or trapway cracks the china |
| Acrylic and fibreglass (tubs, showers) | Tolerates cold well | Water left in jet or air lines, or in the trap below |
| Cast iron and stone tubs | Essentially freeze-proof when drained | Trapped water in the waste and overflow assembly |
| Stainless steel sinks | Unaffected | The trap and supply lines beneath the sink |
| Brass faucets and valves | Fine when dry | Water inside the valve body expands and splits the casting; cartridge seals can be ruined |
Faucets and shower valves are the most commonly replaced freeze casualties because water sits inside the valve body by design. If a shower valve in an exterior wall lets go, the repair usually means opening the wall, and it is the rough-in valve rather than the visible trim that gets replaced. Our guide to rough-in valves versus trim explains why those are two separate parts.
Spring startup: pressurize slowly, check everything
Opening the cottage is when problems reveal themselves, so go slowly:
- Close every faucet, then reopen the main or restart the pump slowly.
- With everything off, watch the water meter or pressure gauge; any movement means water is going somewhere it should not.
- Check under every sink, around every toilet base and at every supply stop for weeping connections.
- Run all faucets to flush antifreeze and air, then clean the aerators, which catch debris that startup shakes loose.
- Test outdoor taps while watching the interior wall behind them.
If a fixture did not survive, replacement is usually the sensible path: a split hose bib or a cracked toilet is rarely worth repairing. Confirm dimensions before ordering so you only ship once; our guide on how to read a plumbing spec sheet covers the measurements that matter, and CSA and cUPC certified toilets from brands like TOTO, Duravit and Icera ship across Canada. One code note: the National Plumbing Code of Canada informs local rules, and details like backflow protection on outdoor taps vary by municipality, so confirm requirements locally.
Frequently asked questions
Do I really need antifreeze in every drain trap?
Yes, in every trap that holds water in an unheated building: sinks, tubs, showers, floor drains and toilet bowls. A frozen trap can split or crack the fixture above it. Use non-toxic propylene glycol plumbing antifreeze, never automotive antifreeze, which is poisonous and unsafe for septic systems.
Are frost-free hose bibs foolproof?
No. A hose left attached traps water in the barrel, and an installation without a downward slope keeps the stem from draining. Disconnect hoses every fall, whatever type of tap you have.
My bathroom sits over the garage and gets cold. Should I worry?
Cold rooms rarely damage fixtures on their own, but supply lines in that floor or in exterior walls are a genuine risk. Insulate the joist bays, keep some heat in the garage during cold snaps, and let the vanity faucet trickle overnight in extreme cold. A pipe that has frozen once will freeze again unless something changes.
Can I just pour antifreeze in the toilet tank instead of draining it?
Drain first, always. Empty the tank and bowl as far as possible, then add plumbing antifreeze to the bowl to protect the trap. Leaving a full tank over winter is the most common way cottage toilets crack.
