Could anyone give me some history or facts on exactly what a lateral sewer line is? Would this be the pipe that is mounted on the wall in the basement or is there another line that is under ground? I was told to have my lateral line checked but I want to know what I am talking about before I call the plumber All I know is that I smell sewer under the front and back porches. This may be coming from the neighbor. I am not sure. I am calling the plumber but I need someone to explain what the lateral line is. This website is great and I appreciate everyones input. Thanks a bunch.