Iron and manganese in a water supply causes a red-black staining on all it comes in contact with. Many waters with these elements also have hydrogen sulfide gas (rotten egg odor).
These elements can be removed from the water supply by Filtering water through Manganese Green Sand. Manganese Greensand is oxygen charged sand that converts ferris iron (in liquid) to ferric iron (solid state) so it can be filtered. Oxygen is depleted from the green sand as iron bearing waters pass through it and must be replaced by injection of potassium per-manganate (KMnO4), and or Chlorine.