[ohthanks]

There are no official treatment recommendations for PFNA, PFOA, PFOS that I know of but they can be treated with activated carbon, RO membranes or some combination. GAC seems to be pretty effective and you could feel pretty safe with a Brita filter, a multi-stage undersink system or a large whole house filter.

The issue with chemicals like these and treatment is that without extensive testing there isn't much information about breakthrough rate and contact time and the relationship, so repeated testing is really the only way to know when you need to change media.

Manufacture cartridge change recommendations generally are pegged to chlorine removal only, so a filter may deplete it's PFOA removal potential in a 1/10 the recommended change interval.