Ultra-short-chain PFAS, the C2-C3 kind like trifluoroacetate (TFA), show up in German and global drinking water sources. We’re talking significant amounts. They’re super water-soluble, move around easily, and conventional treatments like activated carbon barely touch them. Plus, they’re mostly unregulated and stick around in the environment forever. Want to get rid of them? Reverse osmosis and nanofiltration are your best bet, kicking out over 90% of these tough contaminants.