I am putting a bathroom in my shop and need to tie the line into the septic system. My installer left me a "t" at the septic system to tie in. My question is does anyone know what size line I need from the toilet to the septic. I've heard 3 inch but don't know. This bath won't be used that much. Because of the elevation I also need to put a sump pump in for the line. If anyone has done this or has knowledge you comments would be appreciated.