Contaminants in surface and ground waters that serve as sources of drinking water may be quite varied and may cause a range of health effects in children, including acute diseases such as gastrointestinal illness, developmental effects such as learning disorders, and serious long-term illnesses such as cancer.⁶² The U.S. Environmental Protection Agency (EPA) sets drinking water standards designed to protect people against adverse health effects. These standards currently include Maximum Contaminant Levels (MCLs) and treatment technique requirements for more than 90 chemical, radiological, and microbiological contaminants.⁶³ One way to gain insight into children's potential exposure to drinking water contaminants is to look at community water system compliance with these standards. The EPA's drinking water regulations require public water systems, including community water systems, to monitor for compliance with Federal health-based standards and treat their water if needed to meet standards. About 13% of the population receives drinking water from private water systems that are not required to monitor and report the quality of drinking water.⁶⁴

Indicator PHY3: Percentage of children served by community water systems that did not meet all applicable health-based drinking water standards, 1993–2021

• The percentage of children served by community drinking water systems that did not meet all applicable health-based standards declined from 20% in 1993 to about 5% in 2001. Since 2002, this percentage has fluctuated between 5% and 12% and was 7% in 2021.
• Drinking water is a source of lead and copper exposures for children. The percentage of children served by community drinking water systems that did not meet the health-based standard for lead and copper was about 3% in 1993 and less than 1% in 2021.
• Coliforms indicate the potential presence of harmful bacteria associated with infectious illnesses. The percentage of children served by community drinking water systems that did not meet the health-based standard for total coliforms was about 10% in 1993 and less than 1% in 2021.
• Disinfection byproducts are formed when drinking water disinfectants react with naturally occurring organic matter in water. In 2021, about 1% of all children served by community water systems were served by systems that had violations of the disinfection byproducts standard. Exposure to disinfection byproducts may lead to cancer or developmental effects.⁶⁵

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