A burst pipe under a slab or in the yard shows up as a water meter that moves with every fixture off, damp or warm floor patches, pooling or soft ground, or a sudden pressure drop. Close the main and find out whose pipe it is: the municipality usually owns the line to the property line. Leak detection finds the spot; repair means excavation, trenchless replacement or a reroute.
- Check the meter first: a buried leak often shows nowhere inside the house except on the meter.
- Municipalities usually own the service line to the property line; the owner pays for the private side.
- Water pooling on the street, boulevard or sidewalk is a municipal report, not a plumber call; in Calgary it is 311.
- Under a slab, rerouting the line overhead is routinely compared with breaking the concrete; the plumber should price both.
- Utility locates mark public lines only; your own water service and irrigation lines need a private locate before digging.
01 /What are the signs of a burst pipe under a slab or in the yard?
The water meter moving with every fixture off is the clearest sign, because a buried leak may not be visible anywhere. Other signs depend on where the pipe runs.
| Location | What you may notice |
|---|---|
| Under a basement or slab-on-grade floor | Damp or warm patches on the floor, cracked or lifting floor coverings, water at the floor edge, sound of running water near the floor |
| Water service line in the front yard | A soggy strip or sinkhole along the line, unusually green grass in a dry spell, water bubbling at the surface in winter |
| Under a driveway or walkway | Water seeping from joints or cracks, settling or heaving slabs |
| Garage or unheated addition | Water coming up through slab cracks, ice forming on the floor |
| Anywhere on the service | Sudden drop in pressure at every tap, a higher water bill, air or discoloured water after the break is repaired |
A hot water line under a slab gives an extra clue: a warm spot on the floor and a water heater that seems to run constantly. A cold line leak usually shows only through the meter and dampness.
02 /Who is responsible for a burst water line outside the house?
It depends which side of the property line the break is on. Most Canadian municipalities own the water main and the service connection up to the property line or the service valve, and the owner is responsible for the line from there into the house. Calgary's water pages set out that split: the City is responsible for the service line from the main up to the homeowner's property line, service valves are owned and operated by The City, and the lines from the service valve to the building are the owner's.
| Where water appears | Likely owner | First call |
|---|---|---|
| Street, boulevard, sidewalk or neighbour's side | Municipality | Your municipal water line; 311 in Calgary |
| Your front yard between the property line and the house | Owner | A plumber, after confirming with the municipality |
| Inside the foundation or under the floor | Owner | A plumber |
| Unclear, or you have no water at all | Unknown | The municipality first, to check the service valve and main |
Calgary asks residents to call 311 if they have no water, or see water pooling on the grass, road or sidewalk, and says that where a break is on private property, repairs are the owner's responsibility. Municipalities elsewhere use their own terms; confirm with yours before paying for excavation.
03 /How do plumbers find a leak under concrete or in the ground?
With leak detection: isolating sections of the system, pressure-testing them, and then listening for or tracing the escaping water through the surface. The goal is to open one small area, not to jackhammer a basement.
| Method | What it does | Best for |
|---|---|---|
| Isolation and pressure testing | Closes off branches and watches pressure drop to show which run leaks | Deciding hot versus cold, or which branch |
| Acoustic listening | Ground microphones pick up the hiss of water escaping under pressure | Slabs and yards with a pressurised line |
| Thermal imaging | Shows warm patches from a leaking hot line | Hot lines under slabs |
| Tracer gas | A safe gas is pushed into the drained line and detected where it escapes at the surface | Quiet leaks or noisy sites |
| Line tracing | Electronic locating of the pipe route | Finding where the line actually runs |
Ask for a written result that shows the method used and where the leak was found. It supports the repair plan and the insurance claim, and it helps if the first opening misses.
04 /Should a slab leak be repaired or rerouted?
Both options should be priced, and the answer often turns on the age of the pipe and how much finished floor is in the way. A spot repair opens the concrete over the leak, fixes the pipe and patches the slab. A reroute abandons the buried section and runs new pipe through walls or ceilings, where it can be reached in future.
The Burst Pipe Repair Matcher flags this choice for any under-slab location, noting that leak detection comes first and a reroute is often compared with breaking the slab. If you do reroute, keep the new pipe out of exterior walls and unheated spaces.
05 /How is a burst water service line in the yard repaired?
By excavating at the break and replacing the damaged section, or by replacing the whole private line if it is old or has failed more than once. Water service lines in cold climates are buried deep to stay below the frost; Calgary notes that winter frost depths typically range from two to three metres and that pipes are buried around three to four metres deep. Digging that deep needs shoring and a crew, not a shovel.
- Spot repair: excavate at the leak, cut out the damaged section and join new pipe with couplings rated for buried service.
- Full replacement by open cut: trench from the property line to the foundation and lay a new service line.
- Trenchless replacement: pull a new line through the old path with pits at each end, where soil and the old pipe allow.
- Permits and inspections: replacing water lines is permitted work in many municipalities; Calgary lists replacing water and sewer lines as work that requires a plumbing permit.
Restoring the yard, driveway or walkway is part of the cost, and so is any water damage inside if the line leaked into the basement. The ranges are in burst pipe repair cost.
06 /How do you dig safely near a burst service line?
Request a utility locate before any digging, and arrange a private locate for your own lines. In Alberta, Utility Safety Partners takes locate requests online at any time or at 1-800-242-3447 during business hours, with no charge, and asks for at least three full working days of notice before a project. Other provinces run their own locate request services under their own names; ask your municipality which one covers your address.
Emergency repairs by a municipality or a contractor follow their own emergency locate procedures. For an owner, the practical rule is: do not dig, probe or drive stakes along a burst service line yourself.
07 /What about water getting into the basement from outside?
A burst service line can push water along the outside of the pipe and through the foundation where the line enters, or saturate the soil against the wall. That is supply water, but it has travelled through soil, so treat it as grey rather than clean when deciding what to keep.
Once the leak is stopped, the basement follows the normal drying process in the drying guide, with the extra cleaning set out in clean, grey and black water. For Calgary addresses, Calgary burst pipe help collects the City's contacts and rules.
08 /Does insurance cover a burst pipe under the slab or in the yard?
Coverage for the resulting water damage inside may follow the usual sudden and accidental rules, while the cost of digging up and repairing a buried pipe is treated differently from policy to policy. Some policies exclude or limit water entering through foundations, and some offer optional service line coverage. Ask your broker specifically about the buried pipe, the excavation and the interior damage as three separate questions.
The insurance coverage guide explains the underlying tests, and the claim documentation guide shows what to keep, including the leak detection report.
FAQQuestions people ask
How do I know if a water pipe burst under my concrete floor?
Turn off every fixture and watch the water meter. If it keeps moving and nothing is visible, look for damp or warm floor patches and call a plumber for leak detection.
Who pays for a burst water pipe in my front yard?
Usually the owner, if the break is between the property line and the house. The municipality usually handles breaks on its side. In Calgary, call 311 to confirm.
Is it better to reroute or jackhammer a slab leak?
It depends on the pipe's age, how many leaks there have been and what flooring is on top. Ask for a price on both, and favour a reroute when the buried pipe is aging.
Can I dig up my own water line to fix it?
Water service lines in cold climates are often buried very deep, and excavations of that depth need shoring. Public locates will not mark your private line. Hire a plumber and arrange locates.
Why is there water pooling on the sidewalk outside my house?
It may be a break in the municipal main or the city side of your service line. Report it to your municipality; in Calgary, call 311.