How to Drain a Foundation

Lay the course for the drain pipes to extend from the side of the house that has the drainage problem to a ditch or other designated drainage outlet. Plant stakes every few feet and tie a long string around each stake to connect them and create a straight line for guidance when digging.

Dig out a canal next to the side of the house with the drainage problem, using a trenching hoe and shovel. Continue digging along the staked-out course to the drainage outlet. The canal should be 1 foot wide and 1 foot deeper than the foundation footer, to lower the water table. Place plastic tarps a few feet from the digging site and dump the dirt on the tarps. Once the canal is excavated, slope the bottom so water will flow toward the drainage outlet. Dig down another 1/8 inch deeper for every foot of distance toward the outlet. Tamp down the sloped bottom with a manual tamper.

Lay water filtration fabric over the bottom of the canal to block sediment so it can’t clog the perforated pipes.

Scoop a 6-inch layer of 3/4-inch gravel onto the fabric with the shovel. Tamp the gravel down.

Place 4-inch perforated PVC drainage pipes down the middle of the canal. Coat the ends of the pipe and inside the fittings with PVC primer and glue, using a paint brush. Insert the end of the pipe in the fitting and turn it 90 degrees to spread the glue. Continue joining lengths of pipe with glue and elbow, tee or wye fittings, depending on the angle of the connection. Using the correct fittings will make it possible to unclog the pipes with a drain snake if the pipes ever get clogged.

Cover the pipes with 12 to 18 inches of gravel, depending on how deep your pipes are. The more gravel you use, the more sediment and other debris you prevent from clogging the pipes.

Fill in the rest of the canal with the soil you removed. Replant the growth or seed the soil with flood-resistant plants.