How to Install a Sewer Line to a Septic Tank

Understanding the old saying that "all water flows downhill" relates to the installation of the sewer pipe to the septic tank. Except, you do not want a fast flow into the septic tank from the pipe. This condition can cause the water to flow too quickly, leaving the solids behind to clog the drain pipe over time. By following a few basic procedures you can install a sewer pipe into a septic tank at the correct "drop" for proper flow of water and solids.

Difficulty:

Moderately Challenging

Instructions

Things You'll Need

• Transit level
• Transit measure stick
• Sewer pipe
• Shovel
• Clean rag
• Pipe cleaner
• Pipe glue
• Plumbers rope seal

Setting the Fall

1. Use the transit level and shoot the level of the sewer pipe exit point and the septic tank entrance for the pipe by holding the measuring stick at these two points. Calculate the difference of the two measurements. The septic tank entrance level must be lower than the sewer pipe's exit from the home. Understand that the proper "drop" or fall for the sewer pipe into the septic tank should be approximately 1/4 inch for every 10 feet of piping. This amount of fall or drop will properly conduct the solids that are included in every sewer to septic system.

2. Use the shovel to adjust the angle or drop inside the trench with the shovel. As an example, if the sewer line were to run 100 feet from the home to the septic tank entrance, the amount of fall would be 2 1/2 inches.

3. Use the transit to properly adjust every piece of pipe as it is placed in the sewer line trench. You can begin at a "zero" point with the exit from the home and add a negative 1/4 inch to every section of pipe. In other words, at the end of the first 10-foot pipe section you should have a negative 1/4 inch. At the end of the second pipe, the transit should read a negative 1/2 inch and so on.

4. Install the sewer pipe one section at a time and check the amount of fall with each pipe section installation. Adjust the trench depth with the shovel by adding or removing the soil.

Install and Glue

1. Wipe each section of pipe with the rag to remove any dirt and debris where the pipes will mate into each other.

2. Use the pipe cleaner and apply a generous amount of the solvent to thoroughly remove any printing and dirt that the rag did not remove. Allow the cleaner to dry before proceeding to Step 3.

3. Apply the pipe glue to both the male and female portions of the sewer pipe. The male portion will fit into the larger female part of the sewer pipe. Each pipe section will have a male and female part on the opposite ends of the pipe.

4. Slide the two mating parts together while the glue is still wet. Hold the joint in place for about 30 seconds while the glue bonds the two pieces together. Perform this attachment until you reach the septic tank entrance.

5. Place the end of the sewer pipe into the septic tank so the end of the pipe extends approximately three to four inches into and past the interior wall of the septic tank. Seal the gap around the pipe with the plumbers rope seal to hold the sewer pipe in place and create a tight seal to keep dirt and debris from falling into the septic tank.

6. Back fill the trench with the shovel, being careful not to throw any large rocks on top of the new sewer pipe.

Tips & Warnings

• Follow all local and state codes when installing any waste disposal system.

Resources

• Sewer Pipe