Example being the Flint Michigan water fiasco..........
Total screwup by the local and fed govt. EPA! Flint changed it’s source of water to a source that was more acidic. Old lead pipes are usually completely covered inside by mineral deposits, so no lead is exposed. If the water becomes acidic, it eats away themineral deposits and exposes the lead to leaching. I replaced a few supply lines in the Cleveland area that were lead pipes. They looked like Marble inside! At the plant I operated for 30 years, we added Aqua-Mag, which coats everything. We had no lead pipes or lead solder in our system, but had a problem with Iron. If the state and fed epa had been competent, they would have added treatment to the new source water, and there would have been no problems!