EPA sets enforceable Maximum Contaminant Levels or MCLs for the primary standards. EPA delegates the responsibilities for maintaining these levels to the individual Sates. States can choose to adopt the EPA Maximum Contaminant Levels or create more stringent levels for their state. The general categories of the primary drinking water standards include:
- Microorganisms
- Disinfectants
- Disinfectant Byproducts
- Inorganic chemicals
- Radionuclides
