I just looked into this and apparently the city tried to save $51,000 a year, about a$140 per day, by not using orthophosphate which would have corrected the PH imbalance from switching to water from the Flint River which was much more corrosive. This ended up stripping away a decades old film inside lead pipes and actually leaching lead into the water.
It appears that even GM had to stop using water from the Flint River because it was corroding engine parts under assembly line. The doctor that found this had a Masters in Public health and started doing blood work on children after she was tipped off by an EPA employee who was a friend that told her that the Flint water treatment plant was skipping corrosion control in their water treatment. Apparently she held the press conference since publishing this data in a peer reviewed process would have taken a long time And it looks like money saving attempt at $51,000 now costs over one and a half billion to replace the pipes in over 600 million in settlements.