A catch basin is an inlet where excess water quickly enters a drainage system. Installed beneath downspouts and where water accumulates in a yard, the catch basin connects to underground drainpipes, which then distribute the water to a ditch or another safe outlet. Installing a catch basin is a fitting project for do-it-yourselfers with basic tools, as long as you have the strength required to dig out a trench for the drainpipes.
Identify the spot in the backyard where water accumulates, and insert a stake in the center to mark the location for the catch basin. Plan the course for the rest of the system by laying a long rope on the ground from the stake to your designated outlet. Make the course straight and direct.
Lay a plastic tarp along the side of the rope. Use a shovel to cut through the sod and lay it on the trench. With a trenching hoe, dig out an 8-inch-wide by 18-inch-deep trench, dumping the soil on the tarp.
Start at the end of the trench near the spot where the catch basin will go, and dig the trench down 1/8 inch deeper per foot of length at a smooth, consistent slope.
Lay 6 inches of gravel over the bottom of the trench. Place water filtration fabric over the gravel surface.
Set 4-inch-diameter PVC perforated drainpipes in the trench. Connect the joints with "T," "Y" or elbow fittings, depending on the angle needed to connect each length of pipe.
Measure the depth of the catch basin with a measuring stick, and dig out a hole equal to the depth of the basin. Insert the basin so the lid of the drain grate will sit at ground level.
Connect the hole in the side of the basin to the open end of the drainpipe with a "T" or "Y" fitting so the angle is wide enough for a drain snake to fit through if the system ever gets clogged.
Cover the pipes with a 6-inch layer of gravel to block out large debris. Lay filtration fabric over the surface.
Fill the remaining expanse with soil and the sod you removed to dig the trench. Transfer the rest of the soil with a wheelbarrow to fill in a low area of the yard.