PA Drinking Water Regulations - Maximum Contaminant Levels
The Safe Drinking Water Act of 1974, as amended, includes requirements for the Environmental Protection Agency (EPA) to set standards for 83 specific contaminants. The selection is based on the potential for causing adverse health effects and for known or potential occurrence in drinking water. The standards set for each include the Maximum Contaminant Level (MCL) and the Maximum Contaminant Level Goal (MCLG). The MCLG, while not legally enforceable, is a health based standard on the amount of the contaminant in drinking water that the EPA has decided will not endanger human health over a lifetime of exposure. The MCL is established as close to the MCLG as possible and is enforceable for public water supplies but not for private well water supplies. It is the maximum permissible level of a contaminant in water to protect human health.
Water Research Center
...In Drinking Water