Most homeowners are responsible for the line leading from their house to the connection to the main at the street. The main line at the street is the responsibility of the city. A good way to tell if your main sewer line is backing up on your street is to ask the neighbors if they are having any problems with their sewer. Check with the neighbors on each side of you house. If they are also having problems, notify the proper city authority
Write something about yourself. No need to be fancy, just an overview.