Is there any other reason to have a basement back up other than tree roots? I've had a few back ups and as of yet, no plumber has pulled any roots. The City has been out, and they found no problems within the r/w. and the pipes look relatively clean and in order, considering age of house.

Is there any other reason to have a basement back up other than tree roots? Plenty of reasons for your sewer to back up. A broken pipe, a bell in the line causing solids to backeup, a object in the line that's causing paper and solids to collect and back up.
Has you plumber suggested running a Sewer Cam through the line to see if anything's wrong down there?
Good luck, Tom

Hello, linder212... I'm neither a plumber nor an expert on flooding, but I am wondering about a couple of things:

1) Do you live in a flood plain? If so, even when precipitation has ceased, the run-off may be continuing to shed into that area causing the water table to rise. If your home sits in this plain, water levels could be rising underneath it. Typically, it's an problem that seldom rears its ugly head until unusual or persistent weather systems present themselves.

2) Could it be a rise in sediment? Here, in the Mid-Atlantic region, we've been hit with a deluge of precipitation in recent months causing the water table to rise in my area. This rise has created problems with our well by pushing sediment up and into our otherwise perfectly good plumbing. Although we usually never see it, the sediment clogs create drainage issues throughout the house. The tip-off for us is usually browning water, with loads of grit & grime, verging on mud, showing up in the filtration system. When the water table settles back down, the problem vanishes.

I've been in my home more than 30 yrs now and have experienced a sediment issue only once or twice before and never to the extent that I have season. My plumber says that there's nothing that can be done, we merely have wait for things to dry up a bit.