What is a French drain, and how does it function?

A French drain is specifically designed to manage excess groundwater and prevent water accumulation in areas where it is not desired, such as basements or landscaped regions. Its function is achieved through a trench that is filled with gravel and includes a perforated pipe. This setup allows groundwater and surface water to enter the drain through the perforations in the pipe, where it is then redirected away from problem areas.

The gravel surrounding the pipe serves multiple purposes: it provides structural support, facilitates drainage, and helps filter out larger particles, allowing water to flow freely into the pipe while preventing clogs. This design is effective for controlling water flow in a landscape, managing drainage issues, and aiding in soil stability by directing water away from foundations and other critical structures.

Other choices do not accurately represent a French drain—using sand instead of gravel would not facilitate the same hydraulic properties, as sand has different draining characteristics. A drainage pipe without gravel would not effectively manage groundwater flow, and a cylindrical drain placed vertically does not follow the traditional horizontal trench design that defines a French drain. This unique combination of a trench, gravel, and perforated pipe is what makes the French drain highly effective in drainage solutions.