Iron and Manganese Reduction
Iron and manganese are commonly found in well water. Iron and manganese are considered secondary contaminants as they have no direct negative effects on health, although they may cause black or reddish-brown stains on clothes or household fixtures. High levels of iron can also cause metallic tastes in beverages.
Determine what type of iron fouling you have and the concentration of the iron
Iron and manganese in water systems occurs in four forms: ferrous, ferric, organic and iron bacteria. Ferric iron gives the water itself a reddish-brown color and is insoluble in water. Ferric iron usually
appears as rust colored particles floating in the water. Ferric iron precipitates out of water and can be removed inexpensively via particulate filtration. Particulate filtration consists of a filter housing and a sediment filter. A sand filter may also be used for sediment filtration to remove the ferric iron (precipitated rust).
Organic (colloidal) and ferrous iron are soluble in water and therefore cannot be readily removed by particulate filtration alone. Ferrous iron cannot normally be seen in water but will stain clothing when exposed to air. Colloidal iron is made up of very small iron particles (often <0.1 micron) and appears as a reddish-brown color in the water. Colloidal iron will not precipitate naturally. Lower levels of organic or ferrous iron(<= 5mg/l or 5ppm) can be removed with a standard whole house iron filter (greensand filter) or a disposable iron filter. Higher levels of iron greater than 5 mg/l (5ppm)requires aeration (mixing with air) in order to oxidize the ferrous iron into ferric iron so that it may be filtered. Levels of iron greater than or equal to 10 mg/l (10ppm) requires chlorination for adequate oxidation of the iron.
If you suspect that you have organic (colloidal) or ferrous (dissolved) iron in your water, you should test the concentration of the iron in your water with a iron test kit.
Generally 200 to 500 mg/l (ppm) of chlorine is necessary to oxidize the ferrous iron into ferric iron for filtration. Because of this high level of chlorine, it is generally advisable to have a post treatment carbon filter to remove the excess chlorine.
Iron bacteria are not considered a health risk but may give water an off taste or color. Iron bacteria most often appear as stringy, slimy, mucous like substances that may be brown, red or white in color. Iron bacteria thrive on the iron released by corrosion of plumbing components. Iron bacteria can be killed using chemical feed of chlorine (household bleach) either directly into the well or into the water line. Sediment filtration then carbon filtration should follow the chlorine treatment.
