perfluorobutanesulfonic acid (PFBS)
The newly proposed UCMR 5 will expand the list of monitored PFAS compounds to 29.[8] Most PWSs will be affected by this proposed rule and will be required to monitor these compounds, subject to the availability of adequate Congressional appropriations and appropriate laboratory capacity.[9] The monitoring information required under UCMR 5 will provide USEPA with data on the national occurrence of the identified contaminants in drinking water systems, which will be used, along with other available information, to inform USEPA’s future regulatory efforts — including the potential establishment of federally enforceable drinking water MCLs for any of the 29 PFAS compounds identified in the rule, where the data supports the establishment of a regulatory standard.