Each house has its own main sewer line connected to the main public sewer line, of course underground, which is maintained by your city or town.
Water always flows down at an angle down to a bigger trap, sometimes more than one in order to filter and to stop hard materials that are in the sewer pipe system and even oil and fat and grease.
As you can see there is a combination of rain water that comes in from the street to the sewer system collecting water from the road down to a main hub with the option to control the flow and the direction of the water if necessary.
In case you have a septic system, this is not how a sewer septic system runs its more like a collection tank of a sewer and a septic tank needs to actually be emptied, in most cases manually by a truck every once in a while.
We provide Sewer jetting services in NJ.