Introduction Potentially Responsible Parties (PRPs) at per- and poly-fluoroalkyl substances (PFAS) Superfund sites may incur costs for remediating contaminated ground and surface waters to drinking water standards. That cost is unknown, largely because the scope of public water systems (PWS) requiring cleanup is unknown. The Environmental Protection Agency (EPA) has neither identified the universe of Superfund sites with historical PFAS releases to PWS water sources, nor published the maximum contaminant level (MCL) establishing cleanup levels.1 Further, EPA’s third unregulated contaminant monitoring rule (UCMR3) does not identify populations exposed to PFAS concentrations lower than state established MCLs.
The PFAS drinking water remediation cost for a given PWS is also highly uncertain. Attributes including the extent of source contamination, total water demand, influent PFAS concentrations, existing water treatment infrastructure, and nature of the feasible remedial action determine total costs. These attributes—and therefore total costs—can vary significantly across PWS. Minnesota, for example, expects capital and operation and maintenance (O&M) costs to meet its health-based values for five PFAS in seven communities (population 161,000) will average $47 million ($326 million total) and range from $3 million to $153 million.