How to Install an Outdoor Drain System

Types of Outdoor Drainage Systems

The two most common outdoor drainage solutions are French drains and surface catch basins. A French drain is a gravel-filled trench with a perforated pipe that collects and redirects groundwater — ideal for areas with high water tables or soil that retains water. A catch basin (also called a yard drain) collects surface water through a grated opening and channels it through a solid pipe to a discharge point — ideal for low spots where water pools after rain. Many properties benefit from a combination of both systems.

Planning and Layout

Before digging, identify where water collects and determine where you will discharge it. Water can be directed to a storm drain (if permitted by local codes), a dry well, a rain garden, or simply to a lower area of the property away from structures. Plan the trench route to maintain a consistent slope of 1 inch per 8 feet (minimum) toward the discharge point. Call 811 to have underground utilities marked before digging — irrigation lines, gas pipes, and electrical cables are commonly buried in yards.

Installing a French Drain

Dig a trench 12 to 18 inches wide and 18 to 24 inches deep along the planned route. Line the trench with landscape fabric, extending the fabric up and over the sides. Add 2 inches of washed gravel to the bottom. Lay 4-inch perforated pipe (holes facing down) on the gravel bed, maintaining the planned slope. Cover the pipe with gravel to within 4 inches of the surface. Fold the landscape fabric over the top of the gravel to prevent soil from clogging the system. Top with soil and sod or decorative gravel. The fabric is critical — without it, soil particles clog the gravel and pipe within a few years.

Installing Catch Basins

Dig a hole at the collection point large enough for the catch basin box. Set the basin so the grate is flush with the ground surface. Connect 4-inch solid (non-perforated) pipe from the basin outlet to the discharge point, maintaining proper slope throughout. Use PVC pipe with glued joints for the underground run — they are more durable than corrugated flexible pipe. At the discharge point, install an outlet fitting with a pop-up emitter or downspout adapter to prevent animals from entering the pipe. Test the system by running water from a hose into the catch basin and verifying it flows freely to the discharge point.