Iron and Manganese in Household Water and Well Water
If your household water or well water is contaminated with iron and/or manganese, chances are you will know it.
Rust colored stains on your fixtures and clothing, bad tasting and/or smelling water, and maybe even sludge growing
in your toilet tank can all be signs that you have a problem with iron and/or manganese in one form or another.
Regulatory bodies who deal with water issues classify iron and manganese as "secondary" contaminants - those that do
not pose a direct health risk, but instead create problems due to unpleasant odors, tastes, and colors, etc.
Authorities suggest that for ideal comfort and convenience, water with contaminant levels of more than 0.3 ppm (mg/l)
of iron or more than 0.05 ppm (mg/l) of manganese should be treated.
Elevated levels of iron and manganese can affect the flavor and color of water and the food that is cooked in it.
They will react with the tannins in tea, coffee and some alcoholic beverages to product a black sludge that will affect
both the taste and appearance of these beverages.
Iron will often cause yellow to reddish-brown staining of laundry, porcelain, dishes, utensils and glassware. Manganese
will cause similar problems, but results in brownish-black staining. These stains are difficult to remove with common
cleaners, and bleach and alkaline cleaners can actually intensify them.
Iron and manganese can build up in pipelines, pressure tanks, water heaters and water softeners - decreasing the available water pressure and increasing the cost of operating these appliances.
Iron or manganese bacteria can also cause problems in your household. While these bacteria pose no direct threat to
health, they do produce a red-brown (iron) or black-brown (manganese) slime that can accumulate in toilet tanks, pipes
or other appliances and clog your water system. Another unpleasant side-effect of the presence of iron/manganese bacteria
is that they often create hydrogen sulfide as a by-product - giving water an unpleasant "rotten eggs" odor.
There are different varieties of iron and manganese that can be present in your household water supply. Each of
these types must be considered separately, as treatment will be different for each. It should be noted that manganese
is also common in residential water supplies and is usually found in conjunction with iron. It is found in the same forms
as iron, and generally treated using the same methods.
Soluble or Dissolved Iron and Manganese (Ferrous)
This is the most common type of iron (and manganese) found in domestic water sources. It is also called
"clear water iron" because coming out of the tap, the water will look clear and clean (not discolored as it will with
insoluble iron or manganese). If you leave the glass of water for 20 minutes to an hour however, you will notice a
colored precipitate which will eventually settle on the bottom. This is the iron and/or manganese turning back into its insoluble form after coming into contact with oxygen in the air.
Insoluble Iron and Manganese (Ferric)
Ferric iron is simply iron that has already oxidized (rusted) - it can fe readily seen sue to the discoloration of the water or due the presence of tiny granuales of "rust" in the water. Although not as common as it's soluble counterpart, insoluble iron can cause serious problems to those who are afflicted with it.
** Soluble and insoluble iron can often both be found together in a given water sample.
As previously mentioned, iron or manganese bacteria are commonly present in water supplies with large
concentrations of iron, manganese or sometimes calcium present. These bacteria feed on iron or manganese in
the water (and in iron pipes, etc) and produce reddish brown, yellowish or black-brown (with manganese) slime
that accumulates in toilet tanks and in water pipes and appliances. The offensive sludge can also create hydrogen
sulfide, a compound that gives water an unpleasant "rotten eggs" odor that must be dealt with.
If you suspect that you have a problem with iron or manganese in your household water, your first step is to have
the water tested. Test results should let you know the extent of your iron problem, the types of contaminant present,
and the quantities in which those contaminants are present, pH, alkalinity and hardness. Once you have this information,
you can begin to work out the best way to treat your problem.
Again, ideally iron levels should be below 0.3 ppm (or mg/l) and manganese levels should be below 0.05 ppm (or mg/l).
There are a variety of methods available to treat iron and manganese problems. The most effective means in most circumstances is oxidation / filtration. This method is best employed where the combined concentration of iron and manganese is less than 10 mg/l. Common oxidizing agents include chlorine, hydrogen peroxide, and manganese greensand. Essentially, the oxidizing agent causes rapid oxidation or "rusting" of the dissolved iron and manganese causing it to precipitate out of the water and turn into a solid particle. The particle is then mechanically filtered out of the water. We generally recommend manganese greensand as an oxidizing agent because it does not add any unhealthy chemicals to your water (unlike chlorine, for example). Manganese greensand filters are available in different configurations. Most systems employ a large vessel that needs to be backwashed and regenerated on a regular basis, thereby requiring more maintenance and attention from the homeowner. Alternatively, where iron levels are below 5ppm (mg/l), we offer a unique cartridge-style manganese greensand filter which offers a very economical price, excellent performance, and much more convenience (no backwashing or media-regeneration required!). For more information, read our iron water filter page.