Manganese in water is a common, naturally occurring problem but can also be introduced by industry. It can produce a brownish discoloration and have a very unpleasant odor and taste. It may produce black deposits and black filaments. Chlorine bleach should not be used in laundry washed in water with a high iron or manganese content because it can cause stains to set. Currently known cases of manganese poisoning have occurred at elevated levels much higher than levels found in most natural water.
How is it regulated?
Manganese is regulated as a secondary contaminant by the EPA under the Safe Drinking Water Act. The recommended level is 0.05 mg/L, above this level you may experience staining on fixtures, appliances and laundry. High levels will also contribute an unpleasing taste making the water unpalatable.
How can you test for manganese?
There are colorimetric test, which can indicate a presence and a general level. Since manganese can be difficult to remove it is important to have an accurate analysis, so you may want to have samples analyze at a laboratory.
Laboratories analyzing drinking water samples can utilize various methods including EPA method 200.7 and 200.8, which utilize an Inductively Coupled Plasma (ICP) or the Standards Method, 31138 that uses Graphite Furnace.
How can you treat manganese?
Manganese can be problematic to remove because it often is accompanied by iron, hardness and other minerals. Following are some suggestions based upon iron and manganese levels.
- Phosphate compounds (< 3 mg/I combined concentration of iron and manganese)
- Water softener (<5 mg/I combined concentrations)
- Chemical oxidation with potassium permanganate or chlorine; followed with filtration (< 10 mg/I combined concentrations)
- Oxidizing filter (manganese greensand or zeolite or manganese oxide) (<15 mg/I combined concentrations)
- Aeration (pressure) (< 25 mg/I combined concentrations)
