Blocked Drains is probably the most common Plumbing Problem that gets reported on a daily basis. As the Sewer lines gets older there is more maintenance involved. Drains might need a good clean out every 6 months in order to keep the pipe clear of any roots that entered the pipe system.

Roots in Drain Lines.
There are small tree roots that finds an opening in the pipeline be it at the joint or a crack in the pipe. Because there is constant water the roots go down the pipeline and grows there because of the constant water supply. The more roots that grows in the pipeline obstruct the free flow in the pipe causing a blockage.