US drinking water may hold twice the reported PFAS levels, a study estimates

Results below reporting limits are often counted as zero. A model estimating them finds reports capture only 44 per cent of the average concentration of 25 PFAS.

For the six regulated PFAS, the average is about 2.6 nanograms per litre with below-limit results counted as zero, and an estimated 5.2 with the model.

The values are model estimates, and the study does not show what people actually drank or establish a health risk.