I ask because a well-known major service just came and quickly got it draining again but they said they could only use a 2-1/2” tool since that's how big the Cleanout Opening is and yet the PVC just below it is 4” ID as is the clay pipe sections that are beyond the PVC, under the street. Their camera showed that a 2-1/2” hole had been bored thru the roots in the clay pipe, which they say will just grow back over time & clog it again. They suggested their $600 Hydro-Jet cleaning but I'm sure that would need to be re-done on a regular schedule, even if somewhat infrequently. We bought this house new in 1993 and this is the first problem like this. We live on a cul-de-sac with the sewage main in the middle of the circle and there's no trees or bushes anywhere near where the clay pieces of pipe must be buried about 3’-6’ underground. Since I don't know the business, is there a tool that would fit into our 2-1/2" Cleanout Opening that could then be expanded to 4" to get all of the roots out? Also, due to this, I've read lots about using Copper Sulfate to kill roots in drain piping. If I do that to the remaining roots, will it over time just break them off a few at a time and would they then go down into the sewage main? That would sure be an easy do. Will that work? I'm willing to try it by either putting small batches of Copper Sulfate into the toilet to flush it down or even by opening the 2-1/2” Cleanout that's in the garage floor and dumping in the total suggested amount (2-6 lbs?) in there. If that line isn't totally clogged anymore, will those methods actually feed the roots enough Copper Sulfate to kill them or will the Copper Sulfate just flow by the roots too quickly to have any affect? While I'm asking, if I should just use Copper Sulfate alone, how would I know how much Copper Sulfate to use, how often and when should I start it?