PFOS is moderately water soluble, non-volatile, and thermally stable. The potassium salt of PFOS has a reported mean solubility of 680 mg/L in pure water. 2006, Ronald A. Hites, Persistent Organic Pollutants in the Great Lakes, Springer Science & Business Media, →ISBN, page 398:
The new maximum contaminant level goal for PFOA and PFOS — a non-enforceable, health-based goal — will be zero. 2024 April 10, Jen Christiensen, “Biden administration sets first national standard to limit ‘forever chemicals’ in drinking water”, in CNN: