How to Connect a Floor Drain Onto a Septic Tank

Drive a stake into the ground with a mallet above the inlet on the septic tank, if it is not already exposed. The inlet vent is located next to the inlet vent next to the manhole cover on the top of the tank. Drive another stake into the ground where the outlet from the floor drain runs from beneath the house. Tie a string between the two stakes to serve as a guide.

Remove the turf with a spade, if present, along the length of the string a couple of inches wider than the drain pipe you will be using to connect to the tank.

Use a measuring tape to determine the length of the septic pipe run. In order to flow properly, the trench needa to drop 1/4 inch for every 10 feet of length. For example, if the distance between the two stakes is 20 feet, the bottom of the trench by the tank should be 1/2 inch deeper than the top. Dig the trench to specifications, measuring frequently with the tape as you dig. When the trench is complete, you should be able to see both the outlet on the floor drain pipe and the inlet on the septic tank.

Connect a PVC waste joint onto the inlet of the septic tank. This could be an elbow or bend, depending on the connection needed. Clean off the inlet on the tank with a rag and some water. Slip the waste joint over the inlet nipple to make sure it fits. Remove the joint and apply primer to the inside of the joint and the outside of the nipple, followed by glue. Slip the joint into place and hold until the glue sets.

Apply any foundation layer as needed to the floor of the trench. The material required here can vary depending on municipal codes. Spread the material evenly on the bottom of the trench to the depth required.

Cut the PVC sewer pipe to size, if needed, with a saw. As the pipe is cut, sand down any rough sides with sandpaper. Fit the pipe pieces together in the trench and connect with couplings, checking your measurements, before priming and gluing. Run the pipe all the way up to the outlet for the floor drain.

Slip a rubber connection coupling over the floor drain outlet and the end of the septic tank pipe. Tighten each end with a hose clamp.

Fill in the pipe trench with the dirt that was removed previously. Fill around the sides of the pipe first, making both sides are filled equally, before burying the pipe completely. Replace the turf on the top of the trench.