Safe Drinking Water Act

Standards and Measurement

Prior to the 1974 Safe Drinking Water Act, water quality was monitored solely at the state level, and few legal requirements for water quality existed. The 1970s witnessed improvements to the accuracy of water quality testing, allowing small concentrations of contaminants to be detected. In the early 21st century, the EPA sets standards for and regulates both naturally occurring and human-made contaminants, including microorganisms, disinfectants, disinfection by-products, organic chemicals (which are often linked with kidney and liver problems), inorganic chemicals (such as lead and nitrates), and radioactive contaminants. Employing scientific research, the EPA first establishes which contaminants exist in water supplies at concentrations high enough to pose a health risk and then determines which ones to include in the National Primary Drinking Water Regulations. The EPA establishes unenforceable [Page 774]Maximum Contaminant Level Goals (MCLG) for each contaminant. These goals are entirely health based and take into account the risk of exposure to vulnerable populations, such as pregnant women, young children, the elderly, and those with immune deficiencies. Once MCLGs have been established, enforceable standards or Maximum Contaminant Levels (MCLs) are set, considering the known health risks as well as the economical and technical feasibility of complying with the set limit. Efforts are made to ensure that the MCLs are as close to the MCLGs as possible. In some instances, it is not possible to accurately measure the levels of certain contaminants and, instead, the EPA outlines specific methods of water treatment. While the EPA oversees compliance with the SDWA, individual states and Native American tribes can obtain the authority to implement the regulations themselves, as long as they can prove that they will uphold the water quality standards set by the EPA. In the early 21st century, all states, with the exception of the District of Columbia and Wyoming, have received this authority or “primacy.”

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