How to Install Drainage Pipes Under Existing Concrete

Identify the section where water gathers on the driveway surface. Snap two parallel chalk lines across this section. Space the lines so they are 1 1/2 times as wide as the pipes you are using. For instance, the lines should be 6 inches apart for 4 inch pipes.

Remove the section of concrete within the snapped chalk lines. Use a cold chisel and hammer to chip score lines in the surface and use a diamond blade and power saw to cut out sections with clean edges.

Dig a drainage canal 8 inches wide and 16 inches deep on either side of the driveway with a shovel. Both canals should empty onto the street. Slope the canals 1 inch for every 8 feet of length so water will always flow toward the street.

Fill the two side trenches with 6 inches of gravel and tamp it down with a hand tamper.

Remove the top 8 inches of gravel from the trench cut in the driveway. The bottom should be 12 inches below the driveway surface with a layer of gravel base underneath.

Place 4-inch perforated PVC drain pipe in the trench that runs across the width of the driveway and down the length of the two side canals. Use elbow connectors where the corners meet. The final shape of the pipes will form a U with the open end toward the end of the driveway.

Screw a circular grid at the end of the pipe so water can drain through. Cover the pipes with 6 inches of gravel to block debris from seeping down.

Pour new concrete over the gravel. Keep the drainage grid clear.

Fill the remaining expanse along the canals with dirt. Seed the top with grass seed to establish growth that will help absorb water into the system.