Why is there a Belly in my Sewer Line?

There are several reasons why bellies occur in sewer lines. When your house was first built, the sewer line may not have been bedded properly using compacted crushed stone, gravel, or sand. If not bedded properly, pipes sag and bellies form. In the Chicagoland area, there is expansive soil. When pipes are laid on top of unstable or expansive soil, a belly may form when the ground shifts below it. This happens even if the sewer lines were installed properly at the time, because parts of the pipe may settle lower than the rest of the pipe.

A belly in a sewer line can also develop because of improper grading. Sewer lines should slope downward and use gravity to regulate flow and move waste away from your home. Bellies can occur with any sewer pipe material, but typically happen in less rigid types of pipe.

Helpful Tip

Direct Tip: Plumbers may mistake bellies for sewer channeling. Sewer channeling occurs when flowing water cuts a channel into the bottom of a sewer line, sometimes wearing away the bottom of the pipe. Pro services offers free second opinions to provide you peace of mind.