Expert Water Leak Detection & Repair
A water leak that goes unaddressed for even a few hours can damage drywall, flooring, framing, and insulation in ways that cost far more to restore than the original repair. Plomberie 5 Étoiles provides water leak detection and repair across Montreal, Laval, the South Shore, and the North Shore - 24 hours a day, 7 days a week, with a licensed plumber on the call, not an answering service.
From a dripping faucet to a burst copper pipe behind a wall, we locate the source, explain what needs to be done, and complete the repair in a single visit whenever possible.
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Active Leak? What to Do Before the Plumber Arrives
The right actions in the first few minutes can significantly reduce the damage and the cost of repair.
1. Shut off the main water supply. For any active uncontrolled leak, this is the first action. The main shut-off valve is typically located in the basement near where the water supply line enters the foundation - on the street-facing wall in most Montreal homes. Turn it clockwise until it stops. If it's seized or corroded, don't force it - call us and we'll guide you through alternatives while the plumber is en route.
In condos: the shut-off may be behind an access panel in your closet or utility space - or in a mechanical room shared with adjacent units. If you can't locate it, call your building management alongside calling us.
In duplexes and triplexes: your unit may have an individual shut-off on the riser, separate from the building main in the basement.
2. Cut electricity near the water. Water near electrical outlets, the electrical panel, or an electric water heater is a safety hazard. Shut off the relevant circuit breaker before stepping into standing water. When in doubt, shut off the main breaker.
3. If you can't shut off the main valve. The City of Montreal can close the exterior valve (the street-side shutoff) in an emergency. Call 311. They can respond in a few hours on weekdays. In parallel, keep calling us - we often arrive faster.
4. Collect the water where possible. Buckets, towels, and containers under an active drip protect floors and reduce moisture migration into subfloor and ceiling cavities below.
5. Document before cleaning up. Photos and video of visible damage before cleanup are important for an insurance claim. Most Quebec homeowner policies cover sudden accidental water damage - documentation from the first moments is your strongest evidence.
Get a quote Click to callTypes of Water Leaks We Repair
Dripping or Running Faucets
A faucet that drips - even slowly - wastes hundreds of litres per week and can permanently stain the sink basin. The cause is almost always a worn cartridge, a deteriorated O-ring, or a cracked seat washer. Cartridge replacement resolves the problem in a single visit in the vast majority of cases. See our faucet and sink service page.
Leaks Under the Sink or Behind an Appliance
The braided supply hoses connecting the wall valve to the faucet, the P-trap connection at the drain, and the dishwasher discharge connection are among the most common leak points in kitchens and bathrooms. These leaks develop slowly and often stay invisible for weeks - until the cabinet floor is saturated or the subfloor starts to warp.
Leaks Inside Walls or Ceilings
A water stain appearing on a ceiling or wall without an obvious source almost always indicates a leak inside the structure - a pinhole in a copper pipe, a fatigued brass fitting, or a joint that's no longer sealing under repeated thermal expansion and contraction. The critical point: the visible stain is rarely directly above or beside the leak source. Water travels along joists, studs, and vapour barriers before appearing at the surface.
For these leaks we use smoke testing or camera inspection to pinpoint the source before opening anything - which protects your finishes and keeps the repair cost contained.
Water Heater Leaks
An actively leaking water heater is an emergency. Depending on whether the leak is from the pressure relief valve, a supply connection, or the tank body itself, the repair may be a component replacement or a full unit swap. A leaking tank body cannot be patched - it requires immediate replacement. See our hot water tank emergency page.
Toilet Leaks
A toilet can leak in two distinct ways: at the base (worn wax ring between the toilet and the floor flange - visible as water at the floor) or internally (a faulty flapper or fill valve that allows water to run continuously from the tank into the bowl - silent, invisible, and capable of adding hundreds of litres per day to your water bill). See our toilet installation and repair page.
Burst or Pressurized Supply Lines
A supply line failure - whether a copper pipe, PEX line, or braided supply hose - releases water under pressure and can flood a room in minutes. This is always an emergency. The shut-off valve should be closed immediately and the line assessed before pressure is restored. See our water line repair page.
Outdoor Hose Bibs and Exterior Connections
Exterior hose bibs are among the most thermally stressed components in a Montreal home. A bib that wasn't drained and shut off before winter can crack internally and leak inside the wall when it thaws - with no visible exterior leak. If you notice damp drywall near an exterior wall in spring without an obvious source, an outdoor bib that froze and cracked is a likely culprit.
Get a quote Click to callFinding Hidden Leaks - How We Locate the Source Without Unnecessary Demolition
The most technically demanding part of a leak repair is often finding exactly where it is. The visible damage is a clue, not a location.
Smoke testing. We introduce non-toxic smoke into the plumbing system. The smoke escapes at leak points - including hairline cracks, failed joint seals, and stack penetrations that are otherwise invisible. Particularly effective for drain-side leaks, inter-unit leaks in multi-unit buildings, and gas odour investigations. See our smoke test leak detection page.
Drain camera inspection. For leaks involving drain pipes, our HD camera system - integrated with a GPS locator device - identifies the exact location and depth of any failure inside the pipe. See our drain camera inspection page.
Targeted visual access. When the leak location is sufficiently narrowed, we open the minimum area necessary to access and repair the source - a single tile, a small section of drywall - rather than cutting open an entire wall on speculation.
Water Leaks in Montreal Homes - What 15 Years on the Job Has Shown Us
Montreal's housing stock presents leak patterns that aren't common elsewhere. Here's what we find consistently.
Copper and Galvanized Steel Pipe Corrosion
Homes built between 1950 and 1985 across Montreal - NDG, Côte-des-Neiges, Rosemont, Verdun, Hochelaga - typically have copper or galvanized steel supply lines. Galvanized steel corrodes from the inside out, developing pinholes that begin as imperceptible weeping before enlarging into active drips. Copper holds up longer but can develop accelerated pitting corrosion if the local water chemistry or stray electrical currents in the building affect the pipe.
Joint Failures in Older Multi-Unit Buildings
In the duplexes and triplexes of the Plateau, Villeray, Outremont, and Rosemont, connections between the cast iron stacks and copper supply branches often have original rubber gaskets and fittings that are now 50+ years old. These harden and eventually lose their seal - producing leaks in wall cavities between units, in ceiling spaces above ground-floor units, and in pipe chases that haven't been accessed since the building was constructed.
Condensation vs. Leak - A Common Misdiagnosis
In Montreal summers, cold water supply pipes in uninsulated basements produce significant condensation - water that accumulates on the outside of the pipe and drips to the floor. This looks exactly like a leak but isn't one. We identify this on the first visit before recommending any repair work.
Condo Responsibility - Unit vs. Common Stack
In Montreal condo buildings, a leak's location relative to the unit's connection point to the shared stack determines who is financially responsible for the repair. We document leak locations precisely - with photos, written description, and GPS location where applicable - to provide clear evidence for discussions with your condo management or insurer.
Water Leaks and Home Insurance - What You Need to Know
Most Quebec home insurance policies cover sudden and accidental water damage - a pipe that suddenly bursts, a fitting that fails without warning. Key points that affect your claim:
Generally covered: sudden pipe rupture, accidental appliance failure (dishwasher, water heater), a fitting that fails abruptly.
Generally excluded: damage resulting from a known and neglected leak, maintenance failures, and in many policies, sewer backup without a specific endorsement.
What to do: photograph and video all damage before cleanup, call your insurer once the situation is stabilized, and keep all repair invoices. We provide written documentation of the work performed on request - specific enough to support a formal insurance claim.
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Why Choose Plomberie 5 Étoiles for Water Leak Repair
Detection before demolition. We locate the source using smoke testing or camera inspection before opening walls - protecting your finishes and keeping the overall cost down.
Price confirmed before any work begins. Always - even in an emergency.
15 years working in Montreal's buildings. We know the galvanized pipe in the NDG bungalow, the copper fittings in the Plateau triplex, the braided hoses in the Griffintown condo, and the cast iron stack connections in the Rosemont duplex. We're not guessing when we arrive.
CAA-Québec recommended for 10+ years. Verified service quality, every year.
4.8 stars on Google, 145+ verified reviews.
RBQ #5663-4538-01 · CMMTQ Member · Fully insured.