This problem is driving me nuts. About every 4 days our toilet on the first floor seems to clog or drain very slowly. I plunge in quickly about 20 times and then it is ok for another 4 days. This has been going on for about 2 years and I do not know what the problem is. I had a plumber use a snake on it about a year ago but the problem remains. I heard that tree roots can enter a sewage line a cause havoc. We have trees in the front yard where the sewer line runs. Can this be the problem?