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.

Top 10 Causes - Outbreaks in Public Water Systems*

• Giardia
• Norovirus
• Shigella
• Legionella
• Campylobacter
• Copper
• Salmonella
• Hepatitis A
• Cryptosporidium
• Excess fluoride

For a complete listing of water-related surveillance data, see CDC’s Surveillance Summaries for Waterborne Disease and Outbreaks.

* Based on tracking of waterborne outbreaks from 1971-2008. Only confirmed causes have been included in the analyses. For outbreaks with multiple causes, each agent counted toward the total. Outbreak reporting is dependent on capacity to detect, investigate, and report the outbreaks. This requires health effects to be measured and these health effects to be easily linked to water exposure. Clusters of illnesses associated with chronic chemical exposures are not part of waterborne disease outbreak reporting or part of these lists.

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.