Yeah, it was the PH of the source water that Flint switched to that triggered the issues, it dissolved the coating that develops on the inside of pipes (scale).

The city switched back to Detroit water in 2015 (and has since signed a 30 year contract with the succeeding entity that now runs that system) and the state is moving towards requiring eventual replacement of all lead service lines¹.

1. https://www.michigan.gov/documents/deq/deq-tou-dwmad-LeadCop...