I've been reading about the Flint water crisis and it sure sounds like the people running the water treatment plant did not understand some of the basic water chemistry that the people on this forum deal with all the time. I am sure methods of treatment are different, but it sounds like the ph of the water from the Flint river was too acidic and because it was not adjusted properly with the right additives, it corroded the protective layer that forms over the lead in the water lines and copper pipe lead solder. The result was that lead leached into the water that people were drinking.
I am far from an expert on any of this. Any of the chemistry geeks on here have any insight into the matter?