So every year about this time the plumbing in my house stops up for a couple of weeks. There is one bathroom in the house and everything seems to all be linked together (kitchen and bathroom). I have a septic system. I thought it was because the roof vent tube is under a tree and leaves would get in the pipe and clog it up. Every time before when this happened things would drain slow and the toilet wouldn't flush well. This would go on for a couple of weeks and then I would hear a loud WHOOSH and suddenly it would all work great. I thought the leaves had finally decomposed enough to flush down the roof tube thingie and air was flowing again. When I had the new roof put on this summer I had them wrap the top of that tube with screen so no leaves could get in. Problem solved, right? No. A couple of days ago the problem started up again. The tub isn't draining well and the toilet isn't flushing out. When the tub drains I hear a glub glub in the pipes and in the toilet. Same deal when you flush the toilet. There is a glub glub noise from the tub pipes. No water is backing up into the other area. It is just the noise. The kitchen sink is draining really slow as well. Arg! So it can't be that the roof pipe is clogged. What else could be the problem? The system works fine until October/November and then it all backs up for a couple of weeks. It is the weirdest thing.