Introduction
(cont.)
Iron is a common water problem. The chemical/physical nature of iron found in natural water supplies
is exhibited in four general types:
1. Dissolved Iron - Also called ferrous or “clear water” iron. This type of iron can be removed
from the water by the same ion exchange principle that removes the hardness elements, calcium
and magnesium. Dissolved iron is soluble in water and is detected by taking a sample of the
water to be treated in a clear glass. The water in the glass is initially clear, but on standing
exposed to the air, it may gradually turn cloudy or colored as it oxidizes.
2. Particulate Iron - Also called ferric or colloidal iron. This type of iron is an undissolved particle
of iron. A softener will remove larger particles, but they may not be washed out in regeneration
effectively and will eventually foul the ion exchange resin. A filtering treatment will be required to
remove this type of iron.
3. Organic Bound Iron - This type of iron is strongly attached to an organic compound in the
water. The ion exchange process alone cannot break this attachment and the softener will not
remove this type of iron.
4. Bacterial Iron - This type of iron is protected inside a bacteria cell. Like the organic bound iron,
it is not removed by a water softener.
When using a softener to remove both hardness and dissolved iron it is important that it regenerates
more frequently than ordinarily would be calculated for hardness removal alone. Although many
factors and formulas have been used to determine this frequency, it is recommended that the softener
be regenerated when it has reached 50 - 75% of the calculated hardness alone capacity. This will
minimize the potential for bed fouling. (Iron removal claims have not been verified by the Water
Quality Association or Underwriters Laboratories.)
If you are operating a water softener on clear water iron, regular resin bed cleaning is needed to keep
the bed from coating with iron. Even when operating a softener on water with less than the maximum
of dissolved iron, regular cleanings should be performed. Clean every six months or more often if iron
appears in your conditioned water supply. Use resin bed cleaning compounds carefully following the
directions on the container.
5
Caution! Do not use where the water is microbiologically unsafe or with water of
unknown quality without adequate disinfection before or after the unit.
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