Your drain is 40 years old: the signs that say it is finished

Why north-Montreal drains die at 40

Most French drains installed north of Montreal between 1965 and 1985 are porous concrete: perforated concrete sections that water passes through via pores, wrapped in clean stone and often tar felt. The material has an Achilles heel: porous concrete collapses under its own weight once the water table saturates, and the felt clogs with clay mud in 30 to 40 years. The drain becomes a blocked concrete pipe that holds water instead of carrying it.

The result reads every spring: the damp basement, white efflorescence on the walls, the sump pump running 20 times a day in April. The drain breaks nothing on its own — but it holds water against the footing until the crack appears. A 1978 drain clogged with clay mud is a foundation working in water permanently, and a stair-step crack that eventually follows the block joints.

The eight signs of a clogged drain

Sign one: water seeping up the wall-slab joint after a rain over 25 millimetres. Two: the sump pump firing often during thaw, for no apparent reason. Three: a musty or sewer smell in the basement after rain. Four: white efflorescence and damp rings on the foundation walls. Five: mildew behind the basement finishes.

Sign six: a cleanout where water does not leave in the hose test — pour 4 litres in and it pools instead of running off. Seven: new or widening cracks on the walls, a sign waterlogged clay is working the foundation. Eight: sagging ground or a lawn holding puddles along the foundation, a sign the drain stone is saturated. Two simultaneous signs are enough to request the camera inspection.

The camera test: proof by image

French-drain diagnosis goes through the inspection camera: a wheeled borescope lowered into the cleanout that films the drain's full length. The images show the clogging degree — clay mud, roots, collapsed sections — and locate the segments to replace. The report includes video captures and a clear verdict: the drain drains, the drain drains poorly, or the drain no longer drains at all.

The camera test pairs with a flow test: water is poured into the cleanout and evacuation time is measured. A healthy drain evacuates 20 litres in under a minute; a clogged one keeps water on the surface for several minutes. These two measures — image and stopwatch — say whether scraping or high-pressure jet cleaning is enough, or whether full replacement is needed. A porous concrete drain crushed by mud does not get cleaned: it gets replaced.

Clean or replace: the decision rule

High-pressure rotary jet cleaning, with root milling when needed, revives PVC or polyethylene drains clogged with mud: an affordable act, often followed by a re-camera to verify. But on a 40-year-old porous concrete drain, cleaning does not last: the drain stone is saturated with soil, sections are collapsing, and the jet pulverizes a pipe already dead. The rule is simple — clogged PVC or PE: clean; collapsed pre-1985 porous concrete: replace.

Replacement follows the same sequence as waterproofing: excavation to the footing by mini-excavator, damp-proofing membrane on the wall, a 4-inch perforated PVC drain in a bed of 12-to-18 inches of clean stone, geotextile over it, a cleanout at every corner, compacted stone backfill. Full cost prices per house, by wall length and access, and the written warranty covers materials and installation.

The right time to act

The best time to replace a drain is before the crack, not after. When the pump runs 20 times a day every April, the electricity and pump-wear cost (replaced every 5 to 7 years) adds up, and the foundation works in water looking for the slightest weakness. Acting in fall — ground thawed, October rains testing the drain in real conditions — prepares a dry spring.

A waterproofing job with drain replacement often books 2 to 4 weeks ahead in season, and the free camera diagnosis tells you whether your drain drains or holds water. Call 438-544-6364 or send three photos — the cleanout, the basement wall, the yard around — for the camera verdict and the detailed quote.