Water flows away from you in both directions if you live near a divide. I live in South Dakota. We have no measurable levels of PFAS or microplastics in our water system. I have sent samples in myself for testing along with the city's (mediocre) testing. We get water from the Missouri River too, but upstream of that is Montana. We're more at risk of manure in the water system than industrial chemicals at this point. Manure is very easy to filter out for a public water system.