What is manganese?
Manganese is a common, naturally-occurring mineral found in rocks, soil, groundwater, and surface water.
Manganese in the human diet
Manganese is a natural component of most foods, and is an essential nutrient. Eating a small amount of it each day is important to stay healthy. The majority of manganese exposure in the general population comes from food. Grains, beans, nuts, and teas are rich in manganese, and it is also found in infant formula. A normal diet typically provides adequate manganese intake.The principal source of exposure to manganese is from food, but in situations where manganese levels in drinking water are elevated, the contribution from drinking water can increase the overall intake of manganese. Manganese is found naturally in groundwater and surface waters in Iowa. Manganese may become noticeable in water at levels greater than 0.05 milligrams per liter (mg/L, or parts per million), above which level the water may have a brown color and may leave black deposits on sinks and bathroom fixtures.
Adverse human health effects
Some people who may be more sensitive to manganese would be those who absorb greater amounts of manganese or those who excrete less, which includes bottle-fed infants under 6 months old, the elderly, and those with liver disease. Some studies suggest that prenatal and early childhood exposures to manganese can have adverse effects on learning and behavior. When manganese levels in drinking water are above 0.3 mg/L, infants under 6 months of age should immediately stop consuming the water and formula that was prepared with the tap water.
Many years of exposure to high levels of manganese can cause harm to the nervous system, including tremors, shaking, and an unsteady gait, which are characteristic of very high exposure to manganese. The US EPA’s health advisory is intended to protect against this effect.
Manganese is poorly absorbed through the skin. There are not concerns about manganese exposure through skin contact with food or water containing manganese. Anyone concerned about their health from manganese exposure should discuss their concerns with their healthcare provider.
Manganese health advisories in drinking water
EPA has three health advisories for manganese in drinking water:
Acute, short-term health advisory for bottle-fed infants up to 6 months of age, who should not be given water with manganese concentrations greater than 0.3 mg/L for more than a total of 10 days per year. This includes formula made with the tap water.
Acute, short-term health advisory for the general population, who should not ingest water with manganese concentrations greater than 1 mg/L for more than a total of 10 days per year.
Chronic, lifetime health advisory for manganese in drinking water of 0.3 mg/L which is intended to be protective of life-time exposure for the general population.
The US EPA health advisory levels of 0.3 mg/L and 1 mg/L were set based upon typical daily dietary manganese intake levels not known to be associated with adverse health effects. This does not imply that intakes above these levels will necessarily cause health problems. As a precaution, the general population should consider limiting their consumption of drinking water which has levels of manganese above the EPA health advisory to decrease their exposure and to decrease the possibility of adverse neurological effects.
Public Notice examples for manganese are listed on the DNR's Public Notice webpage.
Currently, there is no regulatory limit for manganese in drinking water set by the EPA or the DNR. EPA has set a secondary maximum contaminant level for manganese, which addresses levels that cause aesthetic concerns, such as staining and taste. EPA has set this non-enforceable guideline at 0.05 mg/L of manganese in drinking water. EPA is the process of determining whether to regulate manganese in drinking water due to updated health effects information and additional occurrence data. As part of that process, EPA included manganese in the UCMR4, with monitoring to be completed in 2020. In addition to the occurrence data from UCMR4, EPA will also consider the health effects in their regulatory determination and evaluate potential risks to children and infants based on recent studies.
How do I find out about manganese levels in my drinking water?
If you obtain your water from a public water supply system, contact your public water supply system and request the concentrations of manganese. Please be aware that not all systems are required to test for manganese.
If you obtain your water from a private well and suspect high manganese in your drinking water, contact your local county health department or visit the DNR’s Private Well Program website. This website includes testing and treatment information.
Treatment to remove manganese
Do not boil the water because boiling increases the manganese levels through concentration. Filtration can be effective at lowering manganese levels, however any treatment device requires regular maintenance and cleaning.
The DNR Private Well Program website has treatment information for homeowners, including a reference to the SHL Well Water Quality and Home Treatment Systems brochure. The Iowa Department of Public Health (IDPH) maintains the registry of water treatment devices on their website.
DNR’s Manganese in Drinking Water Fact Sheet and Frequently Asked Questions
EPA’s Office of Groundwater and Drinking Water website
EPA’s Drinking Water Health Advisory for Manganese
EPA’s Secondary Drinking Water Standards website
EPA’s Drinking Water Criteria Document for Manganese website
State Hygienic Laboratory at the University of Iowa Well Water Quality and Home Treatment Systems brochure
Centers for Disease Control’s Public Health Statement for Manganese website (The EPA has updated the manganese health advisories since this was posted)
IDPH Contact Information: For additional health related inquiries regarding manganese in drinking water, contact Stuart Schmitz at 515-281-8707 or email@example.com.
DNR Contact Information: For additional questions or information, please contact the appropriate DNR Field Office:
Field Office 1, Manchester 563-927-2640
Field Office 2, Mason City 641-424-4073
Field Office 3, Spencer 712-262-4177
Field Office 4, Atlantic 712-243-1934
Field Office 5, Des Moines 515-725-0268
Field Office 6, Washington 319-653-2135