City?
Is your new home on a private septic system or on a public sewer system?
Your use of the term "septic lines" have some of us believing that your home is on a septic system, not on a city sewer system.
Septic system drainfield lines have holes in them to drain waste water only into the ground, after the sludge and solids get "trapped" inside the septic tank. Roots can get into those holes.
Segmented drain lines, such as cast iron (going to a public sewer system or a septic system) can get roots into them where the segments meet.
Roots can be "roto-rootered" (cut off inside the pipe with a rotating-head root cutter tool ) and flushed out of segmented drain lines, but septic drainfield lines are dead-ended into the ground.
Roto-rootering will only last a year ot two, and then the roots will come back in a segmented line. Replacement of the segmented drain line, preferably with white plastic PVC or black plastic ABS which have "glued" joints that will not allow roots in, is the only permanent solution for segmented lines with a root problem.
Septic system lines can also be roto-rootered from the distribution box or rom a connection line fromt he d-box for the drainfield feeder lines (both have to be dug up, but they're usually not deep). However, most of the roto-rootred roots will end up at the dead-end of the drain lines. Around here, we don't even do that with plugged drainfield lines. We just go ahead and replace them with new perforated lines in sleeves that help prevent dirt and roots from entering the lines.
Mike