Within the ALCOSAN service area, the sewer system is a complex network of 83 municipal collection systems all flowing to a single treatment plant. The collection system's 4,100 miles of underground pipes collect and transport sewage from each home or business to ALCOSAN for treatment and subsequent release back into the rivers. Laid end to end, these pipes would stretch the distance from Pittsburgh to Phoenix, Arizona and back.
(click for full article at 3RiversWetWeather.org)