Water-related Diseases and Contaminants in Public Water Systems

The United States has one of the safest public drinking water supplies in the world. Over 286 million Americans get their tap water from a community water system (1). The US Environmental Protection Agency (EPA) regulates drinking water quality in public water systems and sets maximum concentration levels for water chemicals and pollutants.

Sources of drinking water are subject to contamination and require appropriate treatment to remove disease-causing contaminants. Contamination of drinking water supplies can occur in the source water as well as in the distribution system after water treatment has already occurred. There are many sources of water contamination, including naturally occurring chemicals and minerals (for example, arsenic, radon, uranium), local land use practices (fertilizers, pesticides, concentrated feeding operations), manufacturing processes, and sewer overflows or wastewater releases.

The presence of contaminants in water can lead to adverse health effects, including gastrointestinal illness, reproductive problems, and neurological disorders. Infants, young children, pregnant women, the elderly, and people whose immune systems are compromised because of AIDS, chemotherapy, or transplant medications, may be especially susceptible to illness from some contaminants.

The Top 10 Causes of Waterborne Outbreaks * in Public Water Systems

• Campylobacter (CDC)
• Copper (CDC-ATSDR, EPA)
• Cryptosporidium (CDC)
• E. coli 0157:H7 (CDC, EPA)
• Giardia (CDC)
• Hepatitis A (CDC)
• Legionella (CDC)
• Norovirus (CDC)
• Salmonella (CDC)
• Shigella (CDC)

For more water-related diseases, see CDC Healthy Water's Water-related Diseases and Contaminants.

* Based on tracking of waterborne outbreaks from 1971-2006. Outbreak reporting is dependent on detection, investigation, and reporting of the outbreak. This requires health effects to be measured and these health effects to be linked to water exposure. However, many contaminants (i.e., many chemicals) in drinking water may not cause easily recognizable outbreaks because they require a long chronic exposure period. As a result, they would not be part of waterborne disease outbreak reporting or part of this Top 10 list.

1. Environmental Protection Agency. Factoids: drinking water and ground water statistics for 2007. March 2008, April 2008. Available at http://www.epa.gov/safewater/data/getdata.html.