Below ground lies a vast network of underground pipes. In
Philadelphia, we have a sewer system that is 3,000 miles long. That’s enough to
stretch from the east to the west coast of the United States.
Philadelphia, like many older cities across the country, has some areas with a combined
sewer system and some areas with a separate sewer system. In a combined sewer system,
sanitary waste and stormwater runoff are collected and travel together through a
pipe to a nearby treatment plant. In a separate sewer system, sanitary waste is
carried in one pipe to a nearby treatment plant and stormwater runoff is carried
in a different pipe that goes directly to a stream.
Combined and Separate Sewer Systems in DRY Weather
Combined and Separate Sewer Systems in WET Weather