Everything you need to know about French drains

Do you have a water seepage problem at home? Have you noticed any mould at the bottom of your foundation walls? Does your basement have a musty smell? You may have a drainage problem. Here is everything you need to know about French drains

Utility of the French drain

The primary purpose of a drainage system is to drain water that has infiltrated around the foundation and prevent it from accumulating. The French drain thus makes it possible to remove any hydraulic pressure in the ground by evacuating the water towards the rainwater or the catchment basin. As the foundation is dry, no water infiltration is possible through the foundation footing.

If the French drain has long proven its usefulness, is it still necessary in all cases? The answer is yes with a few exceptions. If the footing is higher than the ground, like in the case of mobile homes, water will not be able to infiltrate the interior, whether or not there is a drain installed.

Conversely, each time the footing is below ground level, the risk of water infiltration increases if there is poor or no drainage.

Types of drains: agricultural vs PVC drain

Two types of drains can be installed: an agricultural drain (corrugated and flexible plastic pipe) or a perforated PVC drain (rigid and perforated pipe).
Despite its rigidity, the PVC drain does not provide better water drainage than the agricultural drain. However, it is preferred in cases where the soil is contaminated with iron ochre. The reason is very simple: cleaning a smooth pipe is easier than cleaning a corrugated pipe.

Apart from this exceptional case, the proper installation of an agricultural drain or a PVC drain will therefore make no difference to water drainage. Only the total price of the work will be affected.

How to identify a French drain problem?

A drainage problem occurs when the French drain is non-existent or defective, i.e. blocked, crushed or displaced. Other factors such as subsidence and soil type as well as the presence of iron ochre can also cause this type of issue. The different symptoms associated with a French drain problem are:

  • The presence of a white powder called efflorescence
  • The existence of mould at the foot of the foundation walls
  • Presence of water in the basement
  • High humidity in the house
  • A musty smell in the basement

Expert French drain contractor in the West of Montreal

Whether you live in the West of Montreal, Vaudreuil-Soulanges or Valleyfield, you can count on Fondation & Fissure St-Amant team’s expertise for drainage system inspections, excavations, drain unclogging, and French drain installation work. We will meet your needs by offering you tailor-made solutions that respect your budget.

Feel free to contact us for more information. We will be happy to answer your questions.


Work and materials for our Foundation waterproofing and French drain installation services are covered by a 15-year warranty. Crack repairs are guaranteed for a 10-year period. Our warranties are transferable upon the sale of the property.
Certain conditions may apply.