IIRC that was exactly the scenario that happened in Flint, MI in the US. I don't know enough to comment on how it happened, but the end result was that the PH

IIRC that was exactly the scenario that happened in Flint, MI in the US. I don't know enough to comment on how it happened, but the end result was that the PH was too far off and it destroyed something that caused them to leech lead into the water until replaced. Large parts of the city are still unable to use the pipes in their house.