There was a hard cold spell through South Georgian Bay in the first days of this month, and the phone did not ring. It rang on the mild afternoon that followed it, and it did not stop for three days.
That is not a coincidence and it happens every winter.
The mechanism
Ice forming inside a pipe does not usually split the pipe. What splits it is pressure. Water expands as it freezes, and the plug of ice that forms seals the line — so the water still liquid between that plug and the next closed fixture downstream has nowhere to go as it continues to expand. That is what fails the pipe, and it can fail it silently in the middle of the night while everything is still frozen solid.
Nothing comes out yet, because the plug is still in place.
Then the temperature comes up. The plug melts, the line is live again, and mains pressure starts pushing water through a split that has been sitting there for two days. In an occupied house somebody hears it within minutes. In a building in The Blue Mountains that gets used at weekends, nobody hears anything at all.
Why this matters more here than in most places
Environment Canada normals at the nearest reporting station put the Collingwood area at roughly 92 days a year that cross the freezing point and come back. That is a great many cycles, and the escarpment and the shoreline along Nottawasaga Bay do not go through them on the same days — a property at Craigleith can be thawing while one above the brow is still hard. What that produces is covered on the frozen and burst pipe damage page.
Combine that with how much of the housing stock here is visited rather than lived in, and you have the loss that defines this trade locally: an ordinary fitting failure, in an empty building, found somewhere between three days and three weeks later.
The check to make this week
Not during the next cold snap. After the next thaw.
Walk the building with the water on and listen at the main for a meter that will not settle. Look at ceilings under bathrooms, at the floor around the water heater, and at the outside wall where the service enters. Open the cabinet under any sink on an exterior wall. Then look at the crawl space vents, because one left open in November is the commonest single cause we find.
If the property is closed for the season, the whole list is in shutting a seasonal property down against frozen pipes, and it is worth reading before next October rather than this February.
If you find it running
Shut the water off at the main, kill the power to the affected area at the panel rather than at a switch, and photograph the entry route before anything gets moved. What to do in the first hour after water damage is the order to work through, and it applies even when the water has been running for a fortnight.
What does not help is starting to dry the middle of it. After that long the sensible assumption is that materials in contact with the water have failed rather than merely got wet, and the useful first step is finding the edge of the affected area rather than aiming equipment at the visible part.