“Forever chemicals” in public water systems

Under new drinking water guidelines, water systems must shut down wells, treat them, or notify customers if they exceed levels of two chemicals, PFOA and PFOS, over the next year. CalMatters contacted 67 water providers to determine the status of their contaminated wells. PFOA and PFOS concentrations are four-quarter averages in untreated water.

Under old guidelines

30 contaminated wells (2% among all tested) exceed

Under new guidelines

171 contaminated wells (13% among all tested) are projected to exceed

Notes on well statuses: Offline (PFOA/PFOS): The well has been taken offline following PFOA or PFOS detections. Offline (other): The well has been taken offline for a reason unrelated to PFOA or PFOS detections. Added treatment: The well receives some form of additional treatment or blending with other sources of water that can reduce PFOA or PFOS concentrations. In some cases, treatment was added to specifically address PFOA or PFOS contamination; in other cases, it was added to address other chemicals.

Under old guidelines

0.7% of Californiansserved by tested systems with wells exceeding the guideline

Under new guidelines

10.8% of Californiansserved by tested systems with wells projected to exceed

Sources: State Water Resources Control Board; Water providers contacted by CalMatters
Graphic: Youyou Zhou for CalMatters