French drain in Quebec: costs, lifespan, and signs it needs replacement

The French drain is the drainage system that wraps around your home's foundation. When it fails, water comes up into the basement — and the damage quickly outweighs the cost of a full replacement. Here are the numbers and signs to know on the South Shore of Montreal.

What exactly is a French drain?

A French drain is a perforated pipe installed around the foundation, wrapped in gravel (typically 3/4 clean) and geotextile, then connected to a sump pit or the municipal storm sewer. Its job: collect water descending along the foundation and discharge it BEFORE it infiltrates the basement.

What does a French drain cost in 2026 on the South Shore?

Full installation on a standard residential home in Brossard, Longueuil, or Boucherville: $4,500 to $9,500 depending on foundation length, depth, site access, and soil type. Clay soils typically add $800 to $1,500 due to excavation difficulty. Camera inspection of the existing drain: $300 to $600.

Typical lifespan: 30 to 40 years

A properly installed French drain lasts 30 to 40 years under South Shore conditions. Drains from the 1970s-80s (concrete or fibre pipe) have often passed their useful life. Modern perforated PVC drains can last up to 50 years.

6 signs your French drain needs replacing

1) Recurring basement infiltration after every heavy rain. 2) White efflorescence (mineral salts) on interior foundation walls. 3) Persistent musty smell in the basement. 4) Soil waterlogged near the foundation even in dry weather. 5) Water pooling around the perimeter of the house. 6) Camera inspection showing collapsed pipe, heavy buildup, or invading roots. If you check 2 or more, request an evaluation.

French drain vs. sump pump

The French drain collects passively by gravity. The sump pump is installed IN the sump pit and mechanically discharges water when it exceeds a threshold. The two work together. If your lot is very flat or bowl-shaped, a pump is often needed in addition to the drain.

Municipal permit on the South Shore

In Brossard, Longueuil, Boucherville, and most municipalities, a permit is required when the excavation modifies the connection to the municipal storm sewer or the drainage slope. Processing time: 1 to 6 weeks. A professional contractor files this for you.

How long does the job take?

2 to 3 business days for a standard home under normal conditions (loose soil, clear access). Add 1 day for: clay soil, major roots to avoid, or specific landscape backfill. Before/during/after photos and a final camera inspection should be included.