Trees are wonderful. They add beauty, shade, and oxygen. However, they can also invade your sewer line. My friend noticed that his shower water was not draining. He used a borescope to see the location of the. plug, so I knew where to dig with an excavator. Check out the two photos below for more details.

He knew that the location of the blockage was the junction between the 6″ PVC and the 4″ PVC. The installers had used concrete to secure the connection, but over time that concrete had eroded leaving an entry for tree roots. How many roots? See the next photo.
Check out all of the roots! My friend fixed the problem just in time.