The Illinois Environmental Protection Agency (Illinois EPA) has amended its Part 620 Groundwater Quality Regulations to establish state-specific Maximum Contaminant Levels (MCLs) for six per- and polyfluoroalkyl substances (PFAS) in drinking water. The amendments are designed to protect public health by limiting PFAS exposure through drinking water sources and strengthening groundwater quality protections across the state. Under the regulation, community water supplies must conduct monitoring for regulated PFAS compounds and demonstrate compliance with the established MCLs according to the phased implementation schedule.