What is the main difference between MCLG and MCL?

The primary distinction between Maximum Contaminant Level Goals (MCLG) and Maximum Contaminant Levels (MCL) lies in their enforceability. MCLG represents a non-enforceable health goal set by the Environmental Protection Agency (EPA) that provides a target level for contaminants in drinking water, aiming for no adverse health effects. It is based purely on health considerations, without regard for feasibility or cost.

On the other hand, MCL is an enforceable standard established by the EPA that specifies the maximum concentration of a contaminant that is allowed in public drinking water systems. MCLs are set considering both health risks and available technology for monitoring and treatment, making them practical and actionable regulations that must be followed by public water systems. This ensures that the drinking water provided to the public is safe and meets established health and safety standards.

Thus, the clarity around enforceability underscores the critical role of MCLs in maintaining water quality regulation while MCLGs remain as goals that guide these regulations without the force of law.