What is a “Maximum Contaminant Level”, or MCL?
Community water systems are required to provide drinking water that meets standards established under the Safe Drinking Water Act. The U.S. Environmental Protection Agency (EPA) establishes drinking water standards for individual contaminants and groups of contaminants. In establishing an MCL, EPA evaluates studies on health effects (toxicology and epidemiology), studies on the occurrence of the contaminant in water, and studies on the effectiveness and cost of treatment available to remove the contaminant. Based on analysis of this information, EPA sets an MCL.