Why are there “do not boil” and “do not drink” notices issued? A visual look at how toxic compounds can get into the tap and how utilities will determine if it is safe.

Four target contaminants (or classes) with industrial sources were included: per- and polyfluoroalkyl substances (PFAS); 1,4-dioxane; 1,1-dichloroethane; and chlorodifluoromethane (HCFC-22).