Same thing happened in Flint Michigan, the lead pipes weren't the issue; They stopped treating the water a certain way and the slight acidity in the water cause

Same thing happened in Flint Michigan, the lead pipes weren't the issue; They stopped treating the water a certain way and the slight acidity in the water caused (iirc) some sort of calcium carbonate or sodium bicarbonate layer to be washed away until the acidic water started leaching lead into the water.