What clogs a sewer line
A line fills slowly. Sludge and grime coat the walls, mineral deposits harden along them, grease settles in, and roots find a joint and work their way in. Out in the yard, the field line can pick up obstructions of its own.
If snaking isn't getting rid of your blockage, the buildup is still on the pipe walls and the drain needs more than a quick pass. Missed preventative maintenance and stubborn roots are the usual reasons it comes back.
