You may have seen it come out of your own faucet: an unappetizing stream of brown water. It’s likely manganese that’s ended up in the drinking water supply. Manganese is a naturally occurring element in soil and various foods. When found in drinking water, low levels of manganese have been considered an aesthetic concern. It may discolor water, stain plumbing fixtures and laundry, and cause undesirable taste and odor problems.
Changing Regulations
In 1987, the U.S. Environmental Protection Agency (EPA) established a secondary maximum contaminant level (SMCL) for manganese of 0.05 milligrams/liter (mg/L). An SMCL is an unregulated standard for public water systems that communities can use to help manage their drinking water for aesthetic consideration. These standards are threshold values. When these values are exceeded, manganese may cause problems in the drinking water and distribution system.
In 2004, the EPA issued a health advisory to guide communities that may be exposed to drinking water contaminated with high manganese concentrations. This advisory does not mandate a standard for action, rather it provides practical guidelines for addressing manganese contamination.
While manganese is an essential nutrient for humans, the EPA has determined that exposure to elevated levels of manganese in drinking water may result in adverse health effects. Adults drinking water with high levels of manganese may develop impacts to the nervous system and behavioral changes. Infants are particularly at risk because exposure to high manganese levels may cause learning and behavioral problems.
The acute advisory level for infants has been established at 0.3 mg/L for no more than a total of 10 days per year. For adults, the advisory level is established at 1.0 mg/L for no more than 10 days per year. An additional chronic advisory level has been set for any age person at 0.3 mg/L for long-term exposure.
Because of these potentially adverse health effects, the EPA is currently working to determine if manganese should be regulated as a primary contaminant and is working with state agencies to sample for manganese.
What You Should Do.
Unlike other drinking water contaminants such as nitrate, manganese in drinking water comes from minerals in the soil where the water is sourced. So, manganese levels remain fairly consistent over time. However, with the changing regulation and sampling programs implemented by the state, communities need to be aware of their manganese levels and implications for their water systems. Communities with manganese at or above healthy advisory levels in their public water supply should contact their state department and work with their consulting engineer to determine a course of action.
Additional Resources:
EPA Health Advisory Information
Nebraska Manganese Information
(note: hasn’t been updated with EPA health advisory information)
Iowa Department of Natural Resources (DNR) Health Advisory Information