If you live or have a business inside of city limits, you are more than likely on city sewer. The city sewer is a system of underground pipes that direct sewage to a central location to be treated.
If you are building a new home or business you will need a city sewer connection. These must be done by licensed contractors (KamCo is), and require special permits.
Besides connecting to the sewer main, there are also sewer line repairs you may need from time to time. As you can see in the picture, tree roots can be a real problem as well as uncapped cleanouts.
image from northchicago.org