Manganese in Drinking Water: Health Risks, EPA Levels & Removal

What Is Manganese?

Manganese is a naturally occurring metal that is essential for human health in trace amounts — it plays a role in bone formation, blood clotting, and metabolism. However, at elevated levels in drinking water, manganese poses both aesthetic and health concerns. The EPA included manganese in UCMR 4 monitoring (2018–2020) to better understand its occurrence in public water supplies.

Manganese has a secondary maximum contaminant level (SMCL) of 50 µg/L — a non-enforceable guideline based primarily on aesthetic effects (water discoloration, taste, staining). The EPA also has a lifetime health advisory of 300 µg/L and a one-day and ten-day health advisory of 1,000 µg/L for children. In 2024, the EPA issued a drinking water health advisory of 100 µg/L to protect against neurological effects.

Unlike many contaminants, manganese makes its presence known: water with elevated manganese often has a brown, black, or purplish tint and a metallic or astringent taste. It stains laundry and fixtures, and can create black deposits in plumbing.

How Manganese Gets Into Drinking Water

Manganese enters water supplies through both natural and human-made pathways:

• Natural geological deposits: The most common source. Manganese dissolves from rock and soil into groundwater, particularly in regions with manganese-bearing minerals. Anaerobic (low-oxygen) groundwater conditions accelerate dissolution
• Seasonal lake turnover: In surface water systems using reservoirs or lakes, manganese levels spike during fall and spring turnover when low-oxygen bottom water mixes with the water column, releasing dissolved manganese from sediments
• Mining and industrial discharge: Mining operations, steel production, and battery manufacturing can release manganese into nearby water sources
• Agricultural runoff: Manganese-based fungicides (e.g., maneb, mancozeb) used in agriculture can contribute to elevated levels in surface water

Groundwater systems in areas with naturally high manganese geology — including parts of the Upper Midwest, New England, and the Appalachian region — are most commonly affected.

Health Effects

Neurological Effects

The primary health concern from manganese in drinking water is neurological:

• Manganism: Chronic exposure to very high levels causes a condition resembling Parkinson’s disease, with symptoms including tremors, difficulty walking, and facial muscle spasms
• Cognitive effects in children: Multiple epidemiological studies have found associations between elevated manganese in drinking water and reduced IQ, learning disabilities, and behavioral problems in school-age children. The developing brain is particularly sensitive
• Infant vulnerability: Formula-fed infants are at heightened risk because formula reconstituted with manganese-containing water provides a much higher dose relative to body weight than breast milk — see our baby and infant water safety guide for safe formula-prep practices

Aesthetic Effects

At levels above the 50 µg/L SMCL:

• Water discoloration (brown, black, or purple)
• Metallic or astringent taste
• Black staining on laundry, dishes, and plumbing fixtures
• Buildup of black deposits in pipes and water heaters

EPA Regulation Status

Manganese has a secondary MCL of 50 µg/L (non-enforceable, aesthetic-based) and a health advisory of 300 µg/L (lifetime) and 100 µg/L (2024 updated advisory for neurological protection). There is no enforceable primary MCL for manganese at the federal level.

Several states have adopted their own standards:

• California: notification level of 500 µg/L
• Connecticut: action level of 500 µg/L
• Some states enforce the 50 µg/L SMCL as a primary standard

How to Remove Manganese from Drinking Water

Effective manganese removal methods include:

• Oxidation + filtration: The most common municipal approach. Manganese is oxidized (using chlorine, permanganate, or ozone) to form insoluble particles, then filtered out
• Manganese greensand filters: Specialized media filters designed specifically for manganese removal. Effective for whole-house treatment
• Reverse osmosis (RO): Point-of-use RO systems remove 95%+ of dissolved manganese — see the best reverse osmosis systems
• Water softeners (ion exchange): Can remove dissolved manganese, particularly effective when paired with a pre-filter. See softeners vs filters for the right fit
• Whole-house oxidation systems: For severe discoloration, see the best whole-house water filters
• Activated carbon with oxidation: Some carbon block filters with built-in oxidation stages can reduce manganese

Standard pitcher filters and basic carbon filters have limited effectiveness against dissolved manganese, though they may remove particulate manganese (the black particles visible in discolored water).

Frequently Asked Questions

Is manganese in water dangerous?

At levels below the 50 µg/L secondary MCL, manganese is generally not a health concern for adults. However, emerging research suggests neurological effects — particularly in children — may occur at levels previously considered safe. The EPA’s 2024 health advisory of 100 µg/L reflects growing concern about cognitive effects in children. Formula-fed infants are the most vulnerable group.

Why is my water brown or black?

Brown or black water is often caused by dissolved manganese that oxidizes when exposed to air. This is not dangerous at typical concentrations but indicates manganese levels above the 50 µg/L secondary MCL. A whole-house oxidation filter or manganese greensand system can resolve the discoloration.

Can a water softener remove manganese?

Yes, water softeners using ion exchange resin can remove dissolved manganese (in its reduced Mn²⁺ form). However, if manganese has already oxidized to particulate form (visible as black particles), it should be pre-filtered before the softener to avoid fouling the resin. Combining a sediment pre-filter with a softener is effective for most household manganese issues.