I'm specious that any sediment/crust that formed in an old water system may contain very high levels of lead. I think that may be what happened in Flint MI. Cha

I'm specious that any sediment/crust that formed in an old water system may contain very high levels of lead. I think that may be what happened in Flint MI. Changed the PH of the water and all that lead started leaching back into the water.