On April 25th, 2014 the city of Flint Michigan switched it's water supply from the treated water of Lake Huron to the untreated water of the Flint River. The lack of treatment in the water allowed the highly corrosive water from the Flint River to further corrode rusted municipal and privately owned pipes, causing leaching and the release of lead into the water that highly exceeded public safety levels.
The lead contamination of the water supply had significant public health consequences, with many residents, including children, exposed to elevated levels of lead, a potent neurotoxin.
It took over two years to fix the problem.