The Importance of French Drains & How to Install Them

What are French Drains

A French drain is a shallow trench that typically contains perforated pipe and stone, for the purpose of redirecting surface water away from problem areas of your home. The perforated pipe is often referred to as weeping tile or subdrain. 

French drains allow water to pass through easily, preventing it from pooling in low points and trouble areas. Water passes through the stone and into the perforated pipe, where it’s directed with little resistance down a slope to your preferred drainage area.

French drains can be installed by drainage professionals, foundation experts, or if the problem is not directly impacting your foundation, French drains can be installed by the homeowner. Installing a French drain is a frequent DIY project for homeowners, as it can be completed with only a few basic tools and some elbow grease.

Why French Drains are Important

French drains are important because they are an affordable, easy, and effective solution for drainage issues in your yard, around your home, or to help prevent excess moisture in your basement. 

Standing water along the foundation of your home can cause the moisture to slowly leak through and into your basement. It can also cause long-term foundation issues if left untreated. Pooling water throughout your yard can damage or kill your grass and plants, increase the population of insects such as mosquitos, and facilitate the growth of bacteria or mould. 

 With a French drain, excess water can be rerouted and deposited elsewhere, such as a rain garden, water collection tank, or runoff area of your property.

What You Need

This project can be completed with a few simple gardening tools and basic supplies. All of which are available online at ontarioagra.ca or in store at 5377 Elcho Road, Wellandport.

Installing a French drain is a perfect DIY project for those who are willing to put in the work. There are only a few steps and some basic guidelines to help ensure you get the job done right.

1. Dig a trench that’s at least 12 inches wide, and between 18 and 24 inches deep. While digging, remember the goal is to draw water away from certain areas. The best way to do that is to create a slope of approximately 1 inch for every 8 feet. To check the slope as you dig, tie a leveled string between two stakes, and measure the distance between the string and your trench floor. 
2. Fill your trench with a few inches of stone. We recommend ¾” clear stone.
3. Cover the stone with geotextile to help create a weed barrier at the bottom of your trench.
4. Place your primary inlet at the point where water pools the most, to offer the least drainage resistance at this location. Connect your pipe (Subdrain – perforated with sock) to the inlet and lay the pipe along the length of your trench. Remember to place your subdrain with it’s perforation holes facing downward.
5. Backfill the trench with stone until you are a few inches below grade. From here you have two options:
   • Wrap your geotextile over the top of your stones and fill the remaining few inches with dirt. Spread grass seed to make your French drain area blend in with your lawn. This will hide your entire French drain except for the inlet and outlet. 
   • Wrap your geotextile over the top of your stones and fill the remaining few inches with stones that you intend to stay visible as a landscaping feature on your property. This can be done with ¾” clear stone or river rock. 
6. Regularly inspect and clean the inlet grate and outlet point. Flush debris when needed to keep the water flowing freely.