CAPE COD, Massachusetts — Earlier this year, the U.S. Environmental Protection Agency proposed maximum allowable levels in drinking water for six PFAS (per- and polyfluoroalkyl substances) — so-called forever chemicals. Most of the monitored PFAS compounds are terminal compounds. The EPA’s draft drinking water rules are for six terminal compounds that do not degrade under normal environmental conditions. AFFF use is one of the largest sources of PFAS contamination in drinking water. The public comment period for the EPA’s draft PFAS drinking water regulation closes on May 30.