In January 2019, MassDEP announced its intention to initiate the process to develop a drinking water standard, known as a Maximum Contaminant Level (MCL), for a group of Per- and Polyfluoroalkyl Substances (PFAS). As in all regulatory development, MassDEP is bound to follow all applicable statutes, rules and executive orders for rule-making, including public comment procedures. In addition, the Department committed to soliciting stakeholder input ahead of and in addition to the public comment period that accompanies all proposed regulations. Information on MassDEP’s MCL development efforts are available below. The content below includes information on an October 2018 petition for rulemaking to establish a “Treatment Technique” drinking water standard for PFAS that MassDEP received from the Conservation Law Foundation (CLF) and the Toxics Action Center (TAC).