When water shows up in a basement, most homeowners hear one of two answers: replace the French drain, or install a sump pump. Both can be right. Both can also be money spent on the wrong problem, depending on where the water is actually coming from.
A French drain is the perforated pipe that runs along the outside of your foundation footing, bedded in stone and wrapped in filter membrane. Its job is to collect groundwater before it builds up against the wall. In many older homes around Laval and Montreal, that drain is clogged with silt or iron ochre, crushed, or was never installed properly. When it stops working, water finds the cracks and the joint where the wall meets the floor.
A sump pump is a pit and pump inside the basement that collects water from under the slab or from the drain system and pushes it out. It helps when the water table is high or when the drain can't empty to the sewer by gravity. What it can't do is fix a clogged or collapsed exterior drain; it only moves the water that has already reached it.
The clues are usually visible. Water along the base of the walls after heavy rain or spring melt points to the exterior drain. Water coming up through the middle of the slab points to groundwater under the house. Water in one spot often means a crack or a window well problem, which is a smaller repair than either.
The right answer comes from looking, not guessing. A camera inspection of the existing drain and a look at the grading around the house usually settle it. And if the drain does need replacing, that's also the cheapest moment to insulate the foundation from the outside, since the wall is already excavated.