As I recall:.
PFAS is very hard to-remove from water. It takes a LOT of carbon (like one or two 4x20” GAC filters at the faucet) or it takes supercritical water oxidation, which means oxidizing substances are added to PFAS-contaminated water and then the liquid is heated above its critical temperature of 374 degrees Celsius at a pressure of more than 220 bars.
There is no legal maximum amount for drinking water. So municipal water sources lack incentive to add the special filtering needed.
A major source of PFAS is that the FAA requires PFAS to be used in firefighting foam, even though there are alternatives. The foams are used in training and frequently dumped by airports and military facilities. They can do this because, while it is one of the worst pollutants, it is not legally a hazardous substance.
It is made by DuPont.
One of the few legitimate functions of government is to provide or enable clean drinking water, but instead they are causing contamination.
https://en.m.wikipedia.org/wiki/Per-_and_polyfluoroalkyl_substances
This is an excellent filter that gets rid of chloramine and chlorine, along with PFAS-type molecules and VOC:
MATRIKX CHLORAGUARD
https://1ca4c2.a2cdn1.secureserver.net/wp-content/uploads/2022/12/Chloraguard.pdf?time=1681928045
Our local water has chloramines and their byproducts, which are a lot more difficult to get out of the water. This filter now gets rid of PFAS, and I will be getting this when I need to change out my prior version.
Because bacteria can grow on any carbon media, we do need to replace such filters at least yearly, if not sooner, even if we came nowhere near the limits on gallons used.
I also use two filters that eliminate particulates to 0.2 micron or lower, but I do not use reverse osmosis.