Wow that's really scary honestly. The question is, why does the runoff that goes into our storm sewers enter our drinking water supply?
Storm runoff is supposed to enter local streams/rivers/lakes, or so I thought. Regardless, that water contains a lot of other chemicals as well, think about when a garbage truck leaks on your street, or a car is leaking fluids, then you get a heavy rain that rinses everything down the storm drains.