We cover the mechanical components of the septic system such as pumps, so we do not cover the lines.
Line from house - This plumbing is exposed to the elements and can fail from roots, corrosion, freezing, etc.
Leach/field/lateral lines - These lines runs from the septic system into the surrounding ground. They contain no mechanical parts and fail from damage such as freezing, corrosion, tree roots, etc.
Tile fields & leach beds - These are the drainage areas where effluent drains into the ground. These contain no mechanical parts and are mostly trenches filled with gravel.