EPA Publishes Contaminant Candidate List 5 And Includes Broad PFAS Group For First Time

The EPA recently published the Contaminant Candidate List 5 (List 5). It is a list of contaminants that are not currently subject to proposed or final national primary drinking water regulations but are either known or predicted to be present in public water systems. List 5's purpose is to identify contaminants that should be prioritized for regulatory decision making and information collection needs under the Safe Drinking Water Act.

The Safe Water Drinking Act requires EPA to publish an updated list every five years, though EPA has not always abided by that timeline — the last list was published in November 2016. In 2009, EPA placed two specific PFAS, perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), on List 3 for evaluation. In November 2016, EPA issued List 4, which carried over many List 3 contaminants, including PFOA and PFOS, for further evaluation. List 5 includes 66 chemicals, three chemical groups, and 12 microbial contaminants. List