Final answer:
The Environmental Protection Agency (EPA) is responsible for ensuring that public water systems comply with minimum standards for public health, particularly under the Safe Drinking Water Act of 1974 which authorizes them to set and enforce national health-based standards.
Step-by-step explanation:
The agency responsible for ensuring that public water systems meet minimum standards for protection of public health is the Environmental Protection Agency (EPA). Established by an executive order signed by President Richard Nixon in 1970, the EPA's mission is to protect human health and the environment. This extends to the regulation of public drinking water systems under the Safe Drinking Water Act (SDWA) of 1974, which authorizes the EPA to set national health-based standards for drinking water to protect against both naturally occurring and man-made contaminants that may be found in drinking water.
The EPA oversees states, local governments, and water suppliers to ensure compliance with these standards, and it has established maximum contaminant levels (MCLs) to define the levels of contaminants that are legally permissible in water supplied by public systems. The SDWA enabled the EPA to both monitor and regulate public water systems serving more than 25 people, with state agencies responsible for the implementation and enforcement of these drinking water standards. The EPA also manages several programs to protect the public from radiation, including the regulation of radioactive contaminants in drinking water.