Detecting and Investigating Waterborne Diseases and Outbreaks

By collecting data on the types of water, water systems, settings, and agents (what spreads the disease) that are linked to waterborne illness, we improve our understanding of waterborne illnesses and can better guide future prevention efforts.

Although we generally enjoy safe and healthy drinking and recreational water in the United States, waterborne diseases still pose a threat to our health and productivity. We interact with water in many ways during our day-to-day activities. Drinking and household, recreation and leisure, industry, agricultural, and medical uses are just a few examples of our daily interactions with water.

Water contaminated with germs, chemicals, or toxins can lead to waterborne illness if you drink it, breathe it in, or it touches your skin, eyes, ears, or other mucous membranes. A waterborne disease outbreak occurs when two or more people get the same illness from the same contaminated water. Public health officials have been tracking waterborne disease in the United States for more than 100 years, and CDC has been overseeing waterborne disease and outbreak tracking since 1971.

Tracking Disease

Surveillance is the term for tracking illness and injury. Surveillance data help guide efforts to reduce and prevent future outbreaks. Waterborne disease surveillance data have supported national efforts to develop drinking water regulations and have provided guidance for recreational water activities, such as CDC’s Healthy Swimming program.

The national Waterborne Disease and Outbreak Surveillance System (WBDOSS) collects data on waterborne disease and outbreaks associated with recreational water, drinking water, and environmental and undetermined exposures to water. The system collects data on the number of outbreak-associated illnesses, hospitalizations, and deaths; agents; implicated types of water; water systems; and water settings. WBDOSS also collects information on single cases of waterborne illness caused by certain types of chemicals or germs.

Waterborne Disease Outbreak Definition

For an event to be defined as a waterborne disease outbreak

  • Two or more people must be linked epidemiologically by time, location of exposure to water, and type of illness, and
  • This epidemiologic evidence must implicate water as the probable source of illness.
  • Environmental evidence implicating water as the source of infection (for example, water samples testing positive for germs) can strengthen evidence in a public health investigation, but the investigation must find an epidemiologic link between the illnesses and water for an event to be considered a waterborne disease outbreak.