First a little about tree roots: They are always growing, and part of that growth is seeking sources of water. They are very powerful growers and have no problems growing into tight spaces or cracks where they can easily then break pipes apart to access their water. Being as sewer lines offer that, they are a great place for trees to feed themselves.

Now a little about sewer pipes: When sewer lines are installed, the soil around the pipe is typically dug out and backfilled, making it looser than surrounding soil. Roots favor growing in this loosened soil around the pipe. Small breaks or leaks in the sewer lines allow the roots to enter the walls of the pipe. The roots then rapidly grow inside the pipe, taking in the nutrients from the water flowing through the sewer line.

Next, a tip to prevent it: Know where your sewer line is before you plant! We can help you locate it and mark it and then you can plan to plant your trees and shrubs in a different location.

If your home repeatedly experiences plumbing stoppages, you may have roots already growing happily in your sewer line. We regularly cable roots out of lines up here in the great northwest and can get you set up an annual maintenance schedule. We can also camera the line to determine the condition of the pipe and if there are any concerns to keep in mind. If the line is damaged to the point of needing repair, we can help you figure that out too; whether it needs a small patch or a partial or full line replacement.

Source: https://www.clemson.edu/extension/hgic/videos_post...