The plumber found tree roots in my sewer line — what should I do?

Repeated slow drains or backups at the lowest fixture in the house — floor drain, basement toilet, laundry standpipe; gurgling when a different fixture runs; camera footage showing a white fibrous mass like a mop head at a pipe joint; a strip of unusually green fast-growing grass over the lateral in a dry August; blockages that clear after rodding and return on a rhythm of six to eighteen months. Roots do not drill through sound pipe. They find water vapor escaping an already-failed joint or crack, grow in, then thicken and catch paper and grease. So this is really two findings at once: your lateral is broken, and a nearby tree found the break. The pipe defect is the disease and the roots are the symptom — which determines who you should actually be paying.