Manganese in Drinking Water: Black Stains and Health Concerns
How manganese affects water quality and when it becomes a health concern.
More than an aesthetic issue
Manganese causes black or brown stains on fixtures, dark sediment, and a metallic taste. The EPA aesthetic guideline is 0.05 mg/L. Above 0.3 mg/L, health concerns emerge, particularly for infants and children. Research links high manganese exposure to neurological effects in children.
Where it comes from
Manganese occurs naturally in soil and rock. It dissolves into groundwater, especially in low-oxygen conditions. Private wells are most commonly affected. Some municipal systems in areas with manganese-rich geology also have elevated levels.
Treatment
Oxidation filtration (greensand, birm, or air injection systems) is the standard treatment. Water softeners can remove low levels of manganese. Reverse osmosis removes manganese effectively at the point of use. Test your water to determine the level before choosing a system.