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3/18/2025
WT Staff
 Got water questions? Give us a call at 877-52-WATER (877-529-2837), or email us at info@wtga.us
March 18, 2025 433 pm EDT
How much manganese is too much?
Manganese is a hard, silvery metal, an essential nutrient for health when consumed in the diet in trace amounts. Found naturally in groundwater and surface water, manganese is a regulated contaminant in public drinking water around the world.
Health guidance differs from one country to another. The level of manganese in drinking water considered safe for children and adults, with no adverse health outcomes occurring over the long term varies considerably depending where you look and who you ask. The US Environmental Protection Agency (EPA) holds that 1 mg/L of manganese is safe for the short term, consumed in drinking water daily for up to 10 days presumed safe. For long term daily consumption for children and adults, the Maximum Contaminant Level (MCL) is set at .3 mg/L, a legal limit enforced by the US EPA.
Manganese concentration permitted in drinking water, generally accepted as safe for long term consumption by children and adults:
- World Health Organization .4 mg/L
- USA .3 mg/L
- Sweden* .3 mg/L
- Canada .12 mg/L
* Environ Health Perspect 2007 Jul 25;115(11):1533–1538. doi: 10.1289/ehp.10316, Ljung et al.
What's the harm?
Centers for Disease Control (CDC) Toxological Profile for manganese states, "Manganese toxicity can result in a permanent neurological disorder known as manganism with symptoms that include tremors, difficulty walking, and facial muscle spasms. These symptoms are often preceded by other lesser symptoms, including irritability, aggressiveness, and hallucinations. Some studies suggest that manganese inhalation can also result in adverse cognitive effects, including difficulty with concentration and memory problems." Oral exposure through drinking water presents similar symptoms to the inhalation route, most notable in children.
CDC Agency for Toxic Substances and Disease Registry indicates a growing body of evidence showing toxicity harms in babies and children occurring at a level even lower than the SDWA regulation, at .2 mg/L. Considering baby formula often contains manganese, when the bottle is prepared with tap water meeting the SDWA regulations, the combined level can be too high for baby.
Manganese above .05 mg/L may not be harmful to human health, however it does diminish one's enthusiasm for hydration. US EPA has set a Secondary MCL as a guideline for drinking water facilities to protect the aesthetic of tap water for taste and odor, at .05 mg/L. Note Secondary MCL are not mandatory, not enforceable limits under the SDWA. Taste and odor should not be an issue with bottled water. Though not without its challenges, the toxicity of plastic and the high cost, bottled water is regulated by the FDA, the concentration of manganese allowed is .05 mg/L or less.
See prior article on the latest changes to the SDWA, regulation of six PFAS compounds in drinking water, here.
The Safe Drinking Water Act protects public health through the administration and delivery of quality drinking water supplies across the USA. The US EPA establishes standards for drinking water, monitors and enforces treatment techniques for surface water and groundwater, sets maximum limits for around 100 contaminants ensuring public disclosure of deviations and discrepancies.
WaterToday opens the record books of the federal drinking water regulator to bring awareness to the local raw water supply and the compliance record of licensed water treatment facilities. The Georgia Department of Environmental Protection - Division of Drinking Water inspects 2376 licensed and active public drinking water facilities, reporting the results to the EPA. Check back here for drinking water news and alerts as they arise in GA.
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