The wastewater treatment system, also known as the sanitary sewer system, routes wastewater from houses and buildings, to the wastewater treatment plant. The wastewater is treated and cleaned before being discharged into the Cape Fear River. Think of this as the "brush and flush" system.
The storm drainage system transports stormwater runoff from streets and property directly into waterways. The storm drainage system includes streets, storm drains, drainage ditches, pipes, culverts, retention ponds, wetlands, creeks, etc. Remember, stormwater runoff is not treated!
Although not shown on the diagram, there is a third set of pipes underground which carry clean, potable, drinking water to houses and buildings.