Status of the drinking water standards program in the United States

The 1996 Amendments to the Safe Drinking Water Act permit standards to be set on a risk management basis. They are driven by: sound peer reviewed science; availability of adequate data and information; prioritized rule making based on risk; increased stakeholder involvement and regulatory negotiations; cost-benefit analysis; better clarity; timely guidance as to provisions of the standards; and implementation assistance though training and guidance materials. The priority rulemaking activities include: standards for harmful microbiological contaminants, disinfectants and disinfectant byproducts; a ground water rule to protect ground water systems from microbiological pathogens; and standards for radon, radionuclides, and arsenic. Additionally, a contaminant candidate list (CCL) must be published every five years to identify potential substances for subsequent regulation. From the CCL, at least five candidates must be identified to consider for regulation within a five year period. A maximum of thirty contaminants for monitoring by water systems must be published by 1999 and every five years thereafter. Monitoring information derived serves as a basis for future standard setting activities. Drinking water standards are set based on health effects and occurrence information through a two step process. First USEPA establishes a non-enforceable maximum contaminant level goal (MCLG) which is the maximum permissible level of a contaminant where no adverse health effects occur. Once the MCLG is established, a maximum contaminant level (MCL) is promulgated as close to the MCLG as feasible.