Stormwater runoff occurs when rain or melted snow flows over the ground. As stormwater runs over streets, sidewalks, driveways or yards, it can pick up pollution, dirt, and chemicals, especially fertilizers and pesticides from lawns. 

Polluted stormwater can then flow into a storm sewer system or directly into a lake, stream, river, or coastal body of water. Also, any toxic chemicals or hazardous materials that can be carried by water can wash into storm sewer systems or be deliberately dumped into storm drains. Pollution that flows into a storm sewer system can flow into and pollute sources of water for drinking, swimming, and fishing. 

A sanitary sewer overflow is a discharge of raw sewage from a municipal sanitary sewer system. Sanitary sewer overflows can release untreated sewage into basements, streets, or streams before they can reach a treatment facility.

Because sanitary sewer overflows contain raw sewage, they can carry bacteria, viruses, parasites, intestinal worms, and molds. The diseases they may cause range from mild stomach cramps to life-threatening illnesses such as cholera, infectious hepatitis, and severe gastroenteritis.

This description is based on the information found in the Web links listed with this topic.

Web Links from MedlinePlus (National Library of Medicine)
Cryptosporidiosis
Drinking Water
E. Coli Infections
Giardia Infections
Hepatitis A
Parasitic Diseases
Water Pollution

More Links
After the Storm (Environmental Protection Agency)
Basic Information about E. Coli 0157:H7 in Drinking Water (Environmental Protection Agency)
Earth's Water: Runoff (US Geological Survey)
Sanitary Sewer Overflows - Contamination of Drinking Water (Environmental Protection Agency) (PDF — 157 KB)
Sanitary Sewer Overflows Frequently Asked Questions (Environmental Protection Agency)
Stormwater Discharges from Industrial Facilities home page (Environmental Protection Agency)
Stormwater Runoff - Contamination of Drinking Water (Environmental Protection Agency) (PDF — 3.02 MB)
Stormwater Training: (County of San Diego) (PDF — 66 KB)
Why Control Sanitary Sewer Overflows? (Environmental Protection Agency) (PDF — 126.14 KB)

Chemicals in Stormwater
Are these chemicals in MY community?
Acetone
Ammonia
Arsenic
Benzene
Bisphenol A (BPA)
Cadmium
Chlorine
Chromium
Diesel
Endocrine Disruptors
Ethylene Glycol
Ethylene Oxide
Formaldehyde
Gasoline
Lead
Mercury
Methanol
Perchlorate
Perchloroethylene (PCE, PERC)
Persistent Organic Pollutants (POPs)
Pesticides
Phthalates
Polybrominated Diphenyl Ethers (PBDEs)
Polychlorinated Biphenyls (PCBs)
Polyvinyl Chloride (PVC)
Solvents
Styrene
Toluene
Volatile Organic Compounds (VOCs)

Last Updated: January 16, 2013