Hopefully within a year ( [img]/forums/images/icons/smile.gif[/img] ) I will have a Morton building built. I'm considering putting in running water plus a toilet so I won't have to run into the house if I'm all dirty working in the outbuilding. My question is should I use 3" or 4" PVC pipe from the Morton to the septic tank? Throughout the house I have 3" PVC but when it exits the house to go to the septic tank the plumber used 4". I will "tee" into the main 4" PVC prior to it reaching the septic tank. Any pros or cons using either one? Is it code that you have to have 4" under ground? By the way I reside in Maryland. Thanks in advance. Stanley