And how much did the city originally "save"? This affair should be poster child for being pennywise and pound foolish with our infrastructure.
Framing it that way misses an important part of the story. It was the institutional and regulatory failure during the switch away from Detroit city water that made the lead an emergency. Part of the reason that happened is that Flint had depopulated and was basically a failed city. It's not acceptable that it happened, but it didn't happen just because Flint was trying to skimp on infrastructure 40,50,60 years ago.
"By not adding a corrosion inhibitor, Flint was going to save about $140 per day. "
http://theconversation.com/the-science-behind-the-flint-wate...
"Replacement of Flint’s lead service lines, which is the only permanent solution to address its lead vulnerability, is estimated to cost up to $1.5 billion, according to Flint’s mayor, Karen Weaver."