Establishes maximum contaminant levels in drinking water for certain per- and polyfluoroalkyl substances (PFAS); sets such levels at no higher than 4 parts per trillion (ppt) for perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) and no higher than 10 parts per trillion (ppt) for perfluorononanoic acid (PFNA), perfluorohexane sulfonate (PFHxS), and hexafluoropropylene oxide dimer acid (HFPO-DA).