The property line decides everything
A water service pipe runs underground, connecting a building's plumbing to a City water main, and it has two owners. The City's own wording is that it is the City's responsibility from the stand post or property line back out to the city water main, and the homeowner is responsible for the water service from the property line to their basement or water meter.
That boundary is not a technicality. The City handles thawing on municipal property at no charge. Where the work has to happen on private property, the City states that property owners will be charged the cost of work plus 15 per cent. And residents on private streets receive no inspection or thawing services at all, which catches out some townhouse and condominium residents who assume otherwise.
So the first call, when you lose water entirely in January, is 3-1-1 rather than a plumber. The City's First Response Team assesses the situation and establishes which side of the line the freeze is on, and that determines both who does the work and who receives the bill.
The run-water advisory and what it costs you
The City monitors frost depth once daily temperatures consistently drop below zero degrees Celsius, using Environment Canada data, and issues a seasonal run water advisory to vulnerable properties when frost reaches the appropriate depth.
If you receive that written advisory because the City has identified freezing risk on municipal property, you will not be charged extra for the cost of running your water. Your bill is instead calculated on your previous consumption patterns, with final adjustments made, if necessary, between late spring and early summer.
If the freezing risk is on your private property, the position reverses: you must cover the cost of running the water yourself. That is worth knowing before you leave a tap trickling for six weeks on a hunch.
One counterintuitive item from the City's own prevention advice: leave your water service buried. Snow acts as insulation, and clearing snow from above the line allows the frost to drive down toward it. Shovelling a neat path over your water service is actively harmful.
The City's prevention list, verbatim in substance
Keep the heat on, maintaining an indoor temperature of at least eight degrees Celsius even if you are away for a few days. Keep water lines warm by leaving doors open to areas with water lines or the water meter, especially in cooler basements, so heat can circulate.
Insulate pipes near exterior walls, wrapping foam pipe insulation around pipes more likely to freeze, such as those near exterior walls, in crawl spaces or in the attic. Keep the garage door shut, to stop cold air reaching hidden water pipes, which matters in Barrhaven and Riverside South where garages sit inside the house envelope with plumbing in the adjoining wall.
Disconnect outdoor hoses, because while a hose remains connected the outside tap cannot drain and will freeze. Leave the water service buried. And locate your home's interior water shut-off valve and make sure it is operational, which is a task for a mild October afternoon rather than a February emergency.
If it has already frozen
Interior pipes can be thawed manually with heating pads or a hair dryer, working from the tap end back toward the frozen section so that meltwater has an escape route and pressure does not build behind ice. The City's instruction on the alternative is unambiguous: never use an open flame to thaw a frozen water pipe. A torch in a stud bay starts house fires in this city every winter.
Practical steps alongside that. Find the shut-off valve outside the house and clear snow away from it, and clear a path to the interior shut-off valve. Open the tap the frozen line feeds, so you can see when flow returns and so pressure has somewhere to go. If a pipe has already burst, close the main valve first and open the lowest cold tap to drain the system.
Then report it. Call 3-1-1, and take photographs before anything is repaired, because an insurer will want to see the cause and the extent, and a written invoice from a certified plumber describing what failed is worth having on file.
Who should do the repair
Plumber is a compulsory trade in Ontario, trade code 306A. To practise it legally a person must hold a Registered Training Agreement, a Provisional Certificate of Qualification or a Certificate of Qualification, the apprenticeship runs 9,000 hours made up of 8,280 on the job and 720 in school, and a Certificate of Qualification must be renewed to remain valid. Holders appear on the Skilled Trades Ontario public register.
Ask for the name and the certificate, even at three in the morning. Ask for liability insurance and a WSIB clearance certificate as well, since WSIB coverage has been compulsory for most independent operators and sole proprietors in construction since 5 December 2024, with a narrow exemption for work on an existing private residence contracted directly by the occupant.
And ask two practical questions before agreeing to the visit: what is the callout charge, and is it credited against the repair. Both are reasonable to answer on the phone, and a firm that will not answer either is telling you something useful.