With apologies to Mr. Shakespeare, and respect to the American Water Works Association, PFOS and PFOA, only two of the hundreds of "forever chemicals" collectively known as PFAS, are either as concerning as the hundreds of other chemicals identified as "hazardous substances" under Federal law, or they aren't. The current list of "hazardous substances" includes things one might not consider "hazardous" like sodium and silver.
Yes, identifying any PFAS as "hazardous substances" will impose the same liability, subject to the same defenses, on those potentially liable for the release of those PFAS as those potentially liable for the release of any other "hazardous substance". The whole point of the applicable Federal law, the Comprehensive Response, Compensation and Liability Act, also known as CERCLA and the Superfund law, is to cast a very big liability net regarding the costs of responding to releases of such things. Whether or not a particular release is a "substantial threat", as the AWWA suggests should be the trigger for PFAS-related liability, is typically beside the point, at least as an initial matter.
If PFAS, and these two PFAS in particular, are the cause for grave concern, even at barely detectable concentrations, that many state regulators, including in Massachusetts, and courts, and, oh yes, EPA have found them to be, then the same rules that apply to sodium should apply to those PFAS. If they aren't, of course that's a different story.
That won't mean that the Government can't, or shouldn't, assume the costs of addressing the PFAS that are and will be in our environment, but making new exceptions to Superfund liability is for Congress and the President.
“[T]here is clearly defined authority for the EPA to craft a rule that does not simply designate a hazardous substance regardless of the level of the substance, differences in toxicity at different levels, and the risk of exposure to the substance,” AWWA says. “This would ensure that liability for historical and ongoing releases of PFOA and PFOS are limited to those facilities that the EPA has identified as significant sources to the environment with releases posing a substantial threat, as opposed to broadly designating PFOA and PFOS and introducing liability for entities involved in de minimis releases.”