Manganese is one of the most abundant metals in the Earth’s crust and is an essential element for human consumption. But when it comes to its presence in drinking water, manganese brings a whole host of unique considerations ranging from health effects to aesthetic issues. Here are some key facts about manganese as it relates to drinking water.
1. Manganese is found in more than 100 minerals but does not occur naturally in its pure form. It’s often found alongside iron.
2. Manganese is detected nationally in about 97 percent of surface water and in about 70 percent of groundwater, generally at levels below public health concerns. In surface waters, manganese levels are often variable in both concentration and the degree of soluble versus particulate species present. In groundwater, manganese is mostly soluble. Concentration is usually stable in a given location but can vary widely between individual well sources.
3. The U.S. Environmental Protection Agency has set the Secondary Maximum Contaminant Level (MCL) standards for manganese in drinking water at 0.05 mg/L. If manganese is present in amounts above this guideline, water can develop a black to brown color, a bitter metallic taste and leave black stains. The EPA does not enforce Secondary Maximum Contaminant Levels — they are simply guidelines to help public water systems manage drinking water for aesthetic considerations like taste and odor. These contaminants are not considered to present a risk to human health at the SMCL.
4. An AWWARF (now the Water Research Foundation) report from 2006 recommends a finished water manganese level of 0.02 mg/L, and industry experience indicates a finished water manganese level less than 0.015 mg/L is needed to avoid chronic aesthetic issues.
5. Manganese is a needed nutrient for humans to function, but high exposure over periods of time can have adverse health effects, especially for children and the elderly. Exposure to high levels of manganese in drinking water can cause central nervous system problems like tremors and loss of muscle control.
6. The Food and Nutrition Board of the National Academy of Science (NAS) sets an adequate intake for manganese at 2.3 mg/day for men and 1.8 mg/day for women. The upper limit for daily intake is set at 11 mg for adults. The EPA’s lifetime health advisory level is 0.3 mg/L.
7. Especially when combined levels of iron and manganese are relatively high in water, the most effective treatment is oxidation and filtration. AdEdge uses AD26 oxidation/filtration media or ADGS+ coagulation/filtration media for the removal of these contaminants.