Manganese in drinking water, whether tap water or well water, is more than a nuisance. When in water, it can stain laundry and plumbing fixtures along with discoloring the water to an objectionable gray. While gray may be popular for interior decorating, it is not welcome when in the form of manganese staining. As a result of its aesthetic issues, the United States Environmental Protection Agency (US EPA) established a non-enforceable Secondary Maximum Contaminant Level (SMCL) for manganese of 0.05 milligrams per liter (mg/L). The SMCL is essentially a guidance level to provide a threshold below which the unpleasant aesthetic issues would not likely occur.
In addition to the aesthetic issues, manganese in drinking water also has health implications. Manganese in drinking water has been shown to adversely impact neurological development of children, even at levels previously believed to be safe. As a result, the US EPA established a Health Advisory Level for manganese of 0.3 mg/L, meaning that this is considered an acceptable level to consume over a lifetime or as EPA defines “concentrations below which potential health and organoleptic problems would unlikely occur.” The Health Advisory Level is a non-enforceable standard from EPA’s perspective and is provided as guidance. The EPA allows for individual states to establish more stringent regulations.
In Massachusetts, the 0.3 mg/L threshold is being considered by the Massachusetts Department of Environmental Protection (MassDEP) as an enforceable standard. Since about 2013, MassDEP has mandated treatment for manganese removal based on levels of manganese in the finished water supply of public water suppliers. An entity is considered a public water supplier when having at least 15 service connections or serves an average of at least 25 people for at least 60 days a year. This includes water utilities and smaller systems such as schools.
Where is all the manganese coming from? Manganese is a naturally occurring element in the ground and can be present in groundwater and surface water. Additionally, levels of manganese can increase so even if you find a well with low levels now, it may have higher levels of manganese in a couple of years. Once detected in a water supply, the manganese does not typically go away on its own. To remove manganese from water requires a manganese treatment process such as adsorptive media, ion exchange, oxidation/filtration, membranes or biological media.
Should you have questions regarding manganese in drinking water or methods of treatment, please contact ResilientCE at 508-726-2458 or admin@resilientce.com.
Resources:
US EPA manganese in drinking water information:
MassDEP manganese in drinking water information:
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