Ok, so here is my issue... I purchased a house a few months ago that is on a septic system. After we were finished with renovations we moved in and started having issues with the system. The toilets would start to gurgle and the shower would start to fill up while in the shower. We thought there must be a clog in the main line. We called a plumber and had them run a snake through the line and didn't really feel anything, but, it seemed to do the job. The system worked perfectly for 2 weeks... then it all started again... we had the plumber come back out and this time we removed both toilets and ran the snake down both, as well as the shower. He also ran the snake up the line from the outside cleanouts. Again, he didn't really feel anything, but the system started flowing again... Now, 2 weeks later... it's doing the same thing AGAIN! Could this be a roof vent issue? I would think that if it was a venting issue, that if I removed the cleanout cap it would release the pressure and allow the water to flow freely... am I wrong? Please HELP!!!