This fact sheet explains how urbanized areas affect water quality through increased runoff and pollutant loads and what homeowners can do to prevent stormwater pollution.
http://www.epa.gov/npdes/pubs/after_the_storm.pdf
Provides a broad overview of stormwater pollution, including runoff from residential and commercial properties, farms, construction sites, automotive facilities, forestry operations, and others.
Where does the Dirty Water go?
http://www.epa.gov/npdes/pubs/centralized_brochure.pdf#page=2
A rough sketch of where your water goes when it rains.
Protecting your community from sanitary sewer overflows:
http://www.epa.gov/npdes/pubs/ssoenweb.pdf