The SDWA regulates a wide range of contaminants, including microorganisms, disinfectants, disinfection byproducts, inorganic chemicals, organic chemicals, and radionuclides. The EPA establishes Maximum Contaminant Levels (MCLs) or treatment techniques for these substances to protect public health. For example, the MCL for lead is set at 15 parts per billion (ppb), while the MCL for arsenic is set at 10 ppb.
