Manganese in Drinking Water

🩨 Health Effects

No federal primary MCL, but the EPA recommends keeping levels below 0.3 mg/L and has a secondary standard of 0.05 mg/L for aesthetics. Emerging research suggests long-term exposure above 0.3 mg/L may affect neurological development in children and infants.

📍 Sources in Water

Manganese occurs naturally in soil and rock and is common in groundwater, especially in low-oxygen conditions. It also enters water from industrial discharge and natural sediment disturbance.

✅ What To Do

Oxidation followed by filtration is the most effective treatment. Water softeners can help but are not ideal for manganese. Contact your utility if concerned. The EPA is evaluating whether to establish a primary health-based MCL.

📜 Regulation History

Manganese has a secondary MCL of 0.05 mg/L (50 ppb) for aesthetics (black/brown staining and taste). The EPA issued a health advisory of 0.3 mg/L in 2004 for acute exposure and 1 day/10 day exposures for infants. The WHO guideline was 0.4 mg/L but was discontinued in 2011 as levels causing health effects were considered unlikely in typical drinking water.

🔬 How To Test Your Water

Black or brown staining on fixtures and laundry is a visual indicator of manganese. Home test kits cost $10-$20. Certified lab tests cost $15-$25. If you have a private well with low-oxygen groundwater, test for both iron and manganese together, as they frequently co-occur.

💧 Which Filters Remove Manganese?

Oxidizing filters (greensand, birm, or air injection systems) followed by filtration are the most effective whole-house treatment. Water softeners can remove low levels of dissolved manganese. For drinking water, reverse osmosis and NSF/ANSI 53-certified filters can reduce manganese at the tap.

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