What Is Manganese and Where Does It Come From?

Manganese is a naturally occurring mineral found in rocks, soil, and sediment. It is the second most common heavy metal in the Earth's crust after iron and frequently co-occurs with iron in groundwater supplies. Manganese dissolves into groundwater as it passes through manganese-bearing geological formations, particularly under low-oxygen (reducing) conditions.

In surface water, manganese concentrations can fluctuate seasonally. During periods of thermal stratification in reservoirs and lakes, low-oxygen conditions at the bottom can mobilize manganese from sediments into the water column. Seasonal turnover events can then distribute this manganese throughout the water body.

Anthropogenic sources of manganese include mining and mineral processing operations, industrial discharges, and leaching from landfills. Potassium permanganate, a common water treatment chemical, can also contribute to manganese in finished water if applied in excess.

Health Effects of Manganese in Water

Manganese is an essential trace nutrient required for bone formation, metabolism, and antioxidant function. However, excessive exposure through drinking water can have adverse health effects, particularly on the nervous system.

Chronic inhalation exposure to manganese in occupational settings is well-established to cause manganism, a neurological condition resembling Parkinson's disease. Research increasingly suggests that chronic ingestion of manganese through drinking water may also pose neurological risks, particularly to developing children.

Multiple epidemiological studies have found associations between elevated manganese in drinking water (above 0.1 mg/L) and reduced cognitive performance, lower IQ scores, and behavioral problems in school-age children. Infants may be particularly susceptible because they absorb more manganese from the gastrointestinal tract and excrete less than adults.

The WHO established a health-based guideline value of 0.08 mg/L for manganese in drinking water, recognizing the growing evidence of neurotoxic effects from chronic oral exposure.

Regulatory Limits for Manganese in Drinking Water

The EPA SMCL of 0.05 mg/L is a non-enforceable aesthetic guideline. The EPA also issued a lifetime health advisory of 0.3 mg/L and a one-day and ten-day health advisory of 1.0 mg/L for children. Several U.S. states have adopted their own enforceable standards for manganese in drinking water.

How to Test for Manganese in Water

Manganese at concentrations causing aesthetic problems may be evident from black staining, but laboratory analysis is required to determine exact concentrations and guide treatment system design. Standard analytical methods include EPA Method 200.7 (ICP-OES) and EPA Method 200.8 (ICP-MS).

When testing for manganese, samples should be collected in clean, acid-washed containers and preserved with nitric acid to prevent precipitation and adsorption to container walls. Testing for dissolved versus total manganese requires filtering the sample through a 0.45-micron filter at the time of collection.

A complete water analysis including pH, dissolved oxygen, iron, hardness, and alkalinity is recommended, as these parameters directly affect manganese behavior in water and influence treatment system selection.

Treatment Methods for Manganese Removal

Oxidation and Filtration

The most common approach for manganese removal involves oxidation to convert dissolved manganese (Mn2+) to insoluble manganese dioxide (MnO2), followed by filtration. Manganese requires a higher oxidation potential than iron and typically needs stronger oxidants such as chlorine, potassium permanganate, or ozone. A pH above 7.5 generally improves oxidation efficiency.

Greensand Filtration

Manganese greensand and GreensandPlus are catalytic filter media coated with manganese dioxide that both oxidizes and filters dissolved manganese. Greensand filtration systems are the most widely used technology for combined iron and manganese removal in residential, commercial, and municipal applications. Continuous regeneration with potassium permanganate or intermittent regeneration protocols maintain the media's oxidative capacity.

Pyrolusite and Catalytic Media

Pyrolusite (natural manganese dioxide) and engineered catalytic media such as Filox and Pyrolox provide a catalytic surface for manganese oxidation and filtration. These media have a higher manganese removal capacity than greensand and do not require chemical regeneration, though they are denser and require higher backwash rates.

Biological Manganese Removal

Biological filtration harnesses naturally occurring manganese-oxidizing bacteria to convert dissolved manganese to insoluble forms within a filter bed. This approach is increasingly used in municipal water treatment as a lower-chemical alternative to conventional oxidation and filtration.

Ion Exchange

Cation exchange water softeners can remove dissolved manganese at low concentrations. However, if manganese oxidizes within the resin bed, it can cause irreversible fouling. This method is best suited for well water with low manganese concentrations where the water is maintained in a reducing state to prevent oxidation.

Frequently Asked Questions

What causes black staining on fixtures and laundry?

Black or dark brown staining on plumbing fixtures, laundry, and dishware is typically caused by manganese in the water supply. When dissolved manganese oxidizes, it forms dark-colored manganese dioxide deposits. Concentrations as low as 0.02 mg/L can produce visible staining.

Is manganese in drinking water harmful to health?

While manganese is an essential nutrient at low doses, chronic exposure to elevated levels in drinking water has been associated with neurological effects, particularly in children. Studies have linked manganese exposure above 0.1 mg/L to reduced cognitive performance and behavioral issues in children. The WHO health-based guideline value is 0.08 mg/L.

Can a water softener remove manganese?

Water softeners using cation exchange resin can remove dissolved (reduced) manganese at low concentrations, typically below 0.5 mg/L. However, if manganese has oxidized to its insoluble form, it can foul the softener resin. For higher concentrations or combined iron and manganese removal, oxidation followed by greensand filtration is the preferred approach.

Need to Remove Manganese from Your Water?

ForeverPure offers commercial and industrial manganese removal systems, including greensand filters, catalytic media filters, and complete oxidation-filtration systems. Our engineering team can design a treatment solution tailored to your water chemistry and operational requirements.

Contact ForeverPure for a customized manganese removal solution.