How to Dig a Pipe Trench in a Basement Floor

Examine your home's building plans to determine whether there are pipes running through or beneath the basement slab. Plan your trench around any such obstacles to avoid causing damage.

Mark the path of your pipe trench through the basement and to the wall location where you wish to run the pipe to the outside with a piece of chalk. Generally, you’ll want to run the trench through the center of the floor or along any low points to catch as much water in the trench as possible when you need the drainage.

Don safety goggles, face mask, work gloves and steel-toed boots to protect yourself from injury as you dig the trench.

Measure the diameter of the pipe that you intend to install within the trench with a tape measure. Mark two parallel lines along the trench path with the chalk, so they are separated from one another by the measured width of the pipe plus an additional 2 inches to provide room for laying the pipe within the trench.

Cut through the marked chalk lines with a concrete saw. Rent the saw from a home improvement store or equipment rental shop. Align the saw blade along the chalk line, and start the saw. Follow the line with the blade, pushing the saw ahead of you to cut through the slab to the soil below. Turn off the saw, return to the start of the trench, and cut the second line through the concrete.

Sweep up the concrete dust made from the cuts, so you can clearly view the cut lines.

Use a sledgehammer to break up the concrete between the lines along the trench area. Strike the inside of the cut with the sledgehammer, using the weakened edge to aid you in breaking through. Remove the debris from the cut in the concrete. Cut any wire mesh that is running through the concrete with wire cutters. If rebar runs along the length of the trench, use the concrete saw to cut the concrete along the trench into 12-inch-long sections before breaking. The saw will cut through the rebar as well as through the concrete.

Use a trench spade to dig along the trench line to a depth equal to the diameter of the pipe plus 12 inches. Pack the bottom of the trench with a tamper to create a solid footing for the pipe.