Lots of things can block, restrict or damage water and sewer lines. Shifting soil or freezing ground can crack or collapse pipes. A build-up of grease, paper, waste and foreign objects can prohibit proper flow. And the passage of time can cause pipe corrosion or breaks in pipe seals.
One of the most common causes of sewer line back-ups, cracked lines and drainage problems is root infiltration. Roots from trees and larger shrubs enter the sewer line from a joint; they grow and expand to fill up the pipe with a hair-like root mass. The masses quickly become clogged with toilet paper, debris and grease coming from the home to the main sewer line. As the roots continue to grow, they put pressure on the pipe and it will eventually crack.