Manganese is a naturally occuring mineral found in rocks, soil, groundwater and surface water. Manganese is necessary for proper nutrition and is part of a healthy diet, but can have undesirable effects on certain sensitive populations at elevated concentrations. The United States Environmental Protection Agency (EPA) and MassDEP have set and aesthetics-based Secondary Contaminant Level (SMCL) for manganese at 50 micrograms per liter (ug/L), or 50 parts per billion (ppb), and health advisory levels. In addition, EPA and MassDEP have also established public health advisory levels.
Drinking water may naturally have manganese and, when concentrations are greather than 50 ug/L, the water may be discolored and tase bad. Over a lifetime, EPA recommends that people drink water with manganese levels less than 300 mg/L an over the short term, EPA recommends that people limit their consumption of water with levels over 1000 ug/L, primarily due to concerns about potential neurological effects. Children up to 1 year of age should not be given water with manganese concentrations over 300 ug/L, nor should formula for infants be made with that water for longer than 10 days.