From following links in that article to other articles, it looks like those contaminates may have been entering the groundwater everywhere for many years. It was (or maybe still is) being used in Teflon, firefighting foam, fire retardant products, Gortex, stain fighters and other waterproofing products for many years. Those products have been in such widespread use that the contamination is likely everywhere. EPA has been trying to downplay it. They seem to be highly influenced or maybe controlled by industry representatives, especially since the beginning of the Trump administration and the appointment of Pruit to head the agency.