Why not Charge by Actual Sewer Usage?
Because sewage contains a certain amount of solids that would clog the meter. For that reason, water usage is the almost universal method. Also, using the Portsmouth Water & Fire Districts data & meter readers = a considerable cost savings. There may also be direct costs to some properties, depending on the type of collection system in the street. The typical gravity system is a simple pipe from your house to the street. In some areas, however, a gravity system would be so deep that ledge or groundwater would make installation cost prohibitive. In those areas, shallower and smaller pipes in the street may require a pump in your basement or yard. Some such areas might also require a septic tank (but not a leach field). It depends on the specific geography and geology in your area, and might also be determined by the type of treatment system (they are inter-related).
