The immediate cause of the issues in Flint was mismanagement. Treating the source water to moderate the PH would have prevented lead from leaching into it (the cost would have been very small). And then layered on top of that, they didn't need to switch to the source that needed that treatment. And so on.

Removing the possibility of lead leaching into drinking water is an ongoing activity in Michigan, but we are ahead of much of the country at this point (in that we are doing it).

That the US has plumbing that uses lead is of course not unique.

https://www.ctvnews.ca/health/worried-about-lead-in-your-wat...