French Drain Explanation

Definition

• Also known as a dry well, a French drain is a ditch filled with coarse rocks. Ranging from 15 to 20 inches deep, a French drain functions as a storage reservoir for excess water that collects during heavy rainfalls or floods. Although modern French drains contain pipes in addition to rocks, traditional drains only use rocks. Water sits inside a French drain until it seeps through the ground below.

Location

• Dig a French drain in areas where percolation is limited. Identify these areas as those where water naturally collects and pools after rainfall. The land should be flat and away from contaminants, including areas where grease and oil exist.

Materials

• Anyone building a French drain will need an excavation tool, such as a backhoe, as well as a smaller shovel. The drain itself requires rocks or pea gravel that sits at the bottom, along with filter fabric to line the walls. Use a staple gun to help secure the liner. The drain may also require explosives, such as dynamite, to break up the rocks into small, coarse pieces.

Installation

• Identify a flat area of land where the drainage is poor. Dig a hole as deep as possible with the backhoe. Install filter fabric along the walls of the ditch and use staples to keep the filter fabric in place. Once the fabric is secured, drop pea gravel into the ditch with the shovel, leaving about 7 inches of space at the top.