Manganese in Drinking Water

Manganese occurs naturally in PEI rocks and soils. Usually it is not easily dissolved from these sources and its concentration in well water is low. In some cases, particularly in swampy areas where oxygen levels in groundwater are low, manganese is more easily dissolved and can be present in well water at significantly higher levels. Manganese is considered to be an essential element for humans and at the concentrations most often found in groundwater, it is not considered to be a threat to health. For drinking water supplies, Health Canada has established a maximum acceptable concentration (MAC) of 0.12 mg/L in drinking water, and an aesthetic objective level (AO) of 0.02 mg/L.

What are the health concerns?

Some studies have suggested an association between high concentrations of manganese in drinking water and neurological effects in children. Health Canada has reviewed and assessed the health risks associated with manganese and based on this review, a maximum acceptable concentration (MAC) of 0.12 mg/L (120 μg/L), has been established based on effects on infants, the most sensitive population. Although the MAC is based on infants, this value is intended to protect all Canadians.

What are the aesthetic concerns?

Moderately elevated manganese levels can be of concern for aesthetic reasons because of unpleasant tastes, staining of laundry or fixtures and encrustation of water pipes. To minimize these problems, the Guidelines for Canadian Drinking Water Quality include an aesthetic objective (AO) for manganese of 0.02 mg/L. 

What are the treatment options?

Manganese levels can be reduced by the use of a water treatment device. It is recommended that advice from a qualified groundwater professional be sought prior to deciding what solution best meets your situation. Because the aesthetic effects of high manganese concentrations can affect a variety of domestic water uses, usually manganese is treated at the point of entry to the house. The most common water treatment device is a water softener. For treatment at a single point of use, reverse osmosis or pour through filters (e.g., pitcher type of filter) can be used.

The Department does not recommend specific brands of treatment devices; however, it is recommended that you purchase a device that has been certified to NSF/ANSI Standard 42: Drinking Water Treatment Units.  As with the use of any drinking water treatment device, the effectiveness of treatment should be verified by sampling after installation. In addition, it is important to ensure the device is used and maintained according the manufacturer’s directions and its performance periodically confirmed by sampling.