Sample size is 716. Time period was 5 years. The sampling process was carried out by property owners as volunteers and involved several steps. Several detections were at or below limits for current testing methods.
And the study, much more rationally than the headline, concludes:
"Modeled results indicate that on average at least one PFAS is
detected in about 45% of US drinking-water samples. Results also
indicate that 1) detection probabilities vary spatially (8% in rural areas
up to > 70% in urban areas/areas with a known history of PFAS
contamination), 2) drinking-water exposures may be more common in
the Great Plains, Great Lakes, Eastern Seaboard, and Central/Southern
California regions, and 3) temporal variations in concentrations/detections may be limited"
And the study, much more rationally than the headline, concludes:
"Modeled results indicate that on average at least one PFAS is detected in about 45% of US drinking-water samples. Results also indicate that 1) detection probabilities vary spatially (8% in rural areas up to > 70% in urban areas/areas with a known history of PFAS contamination), 2) drinking-water exposures may be more common in the Great Plains, Great Lakes, Eastern Seaboard, and Central/Southern California regions, and 3) temporal variations in concentrations/detections may be limited"