Drinking water can be a significant route of exposure to pathogens and pollutant chemicals.
An effective, mature, and highly regulated public drinking water treatment and distribution industry exists in the United States to protect against these hazards. This industry generates large amounts of water quality data. Water quality is monitored during the water treatment process to comply with State and federal monitoring and reporting regulations. Other data are generated in laboratories and become available over longer periods. Data on nitrates, heavy metals, pesticides, and volatile organic compounds for example may be reported on a frequency ranging from one per month to one per several years depending on the population served and the history of occurrence of regulated contaminants in the water.