The signs of tree roots in a sewer line usually show up as slow drains in more than one fixture at once, gurgling toilets, and clogs that clear but come back within weeks. As roots build up you may also notice a sewer odor, backups into low drains, and a greener or soggier strip of lawn running along the pipe.
The pattern matters more than any single symptom. A clog in one sink is usually local, but slow drains and gurgling across the whole house point to the main line that every fixture shares. Roots do not bore through sound pipe; warm wastewater leaks vapor through an existing crack or loose joint, the roots follow that moisture to the opening, then spread inside and catch grease and paper. Older clay and cast iron joints common in this area are the usual way in.
The clearest tell is a clog that keeps returning. If a line backs up again a few weeks after it was snaked, roots growing back through the same opening are a likely cause, and cutting them alone leaves that opening for the next season. Lasting fixes pair tree root removal with sealing the joint the roots used, while a short term chemical root treatment only buys time between visits.
These signs are not proof of roots. Grease buildup, a sagging belly, or an offset joint cause the same slow drains and backups, so the symptoms tell you the main line is in trouble without naming the cause. A sewer camera inspection is what confirms roots are the problem, shows how many entry points there are, and whether the pipe still has enough structure to line.