At least 5 percent of the earth’s crust is made up of iron, making it one of the most abundant resources as well as one of the most troublesome elements in water supplies.
Iron at normal levels is not hazardous in your drinking water, it is considered a secondary contaminant. In fact, iron is a necessary requirement of our bodies. About 5% of our bodies required iron is supplied by our tap water.
Types of Iron
There are typically two forms of iron and one iron related bacteria:
- Soluble Ferrous Iron – this type of iron is completely dissolved in the water and only after sitting a glass on the counter and watching it will you see it start to turn cloudy. Usually a muddy or reddish substance appears and then sediment begins to settle on the bottom of the glass.
- Insoluble Ferric Iron – When soluble ferrous iron come in contact with pressure, such as in a holding tank, or even in a glass, the sediment that appears is considered insoluble ferric iron. Iron in this form does not dissolve in water. If raw insoluble ferric iron is present, your tap water will generally come out with a reddish or brown tint. If this type of iron is put in a clear container, you will see these particles settle to the bottom of the glass immediately.
- Iron Bacteria – These are actually microorganisms that live in some water supplies. These bacteria feed on the dissolved iron and oxygen present in the water. This action will result in rust looking stains, but also as a byproduct you will see a brown or yellowish slime forming on fixtures such as toilets, faucets or sinks. The slime will usually have an odor that can resemble oil or raw sewage. A great place to look for this slime is on the inside of your toilet tank, providing you are not using sanitizers in the tank.
Taste of Iron
Iron in drinking water may be considered aesthetic, however it definitely does have a nasty metallic taste.
In beverages, it will turn them darker, sometimes blackish and has a very harsh taste. The same holds true for vegetables and other soft foods.
Red Brown Stains
Low concentrations of iron, even those in the 0.3 mg/l can cause staining on fixtures and even clothing when washed.
How does iron get in my water and how do I get it out?
As noted above, about 5% of the crust is made up iron. It gets into water supplies as it rains and the water soaks into the soil and the rocks below. The water will dissolve the iron as it moves though and deposit it into the aquifer. Sometimes it’s introduced through man-made materials such as iron or steel piping.
Treatment for Iron
The treatment options for this parameter are installation of a green sand unit or Iron specific filtration system. Water Softening systems can sometimes lower the level of this contaminant but is not specific treatment for it.