he Safe Drinking Water Act (SDWA) is the primary federal law that ensures the quality of Americans' drinking water. Entities operating a Public Water System (PWS) must comply with the requirements of the SDWA. PWSs are systems with at least 15 service connections or serving at least 25 people for at least 60 days a year (42 U.S.C. § 300f(4)).The U.S. Environmental Protection Agency (EPA) sets standards for the monitoring and treatment of water for regulated contaminants. Under the SDWA, the EPA adopts regulations for contaminants in drinking water that can adversely affect health and that are known or could occur in public water supplies (42 U.S.C. § 300g-(b) (1)). The level at which PWSs must act to address regulated contaminants is known as the Maximum