Iron Bacteria

Iron-related or iron-precipitating bacteria (Crenothrix) are a diverse group of microorganisms widely distributed in nature. They are found in fresh and salt waters, in soils, and on desert rock surfaces. Iron bacteria do not normally cause diseases to humans or animals, but rather, they are a nuisance microorganism.

These bacteria are capable of transforming iron and sometimes manganese to an insoluble form that can cause severe fouling or plugging which reduce flows in pipes and plumbing fixtures, in well pumps, treatment plants, and distribution systems. If your home is supplied by well water, most likely you have, and are, seeing, firsthand, the results of what is meant by this bacteria being a "nuisance" microorganism.

These bacteria are the ones responsible for making that reddish-orange, slimy-looking deposit inside the flush water holding tank on the back of your toilet. These bacteria do not need light or air to proliferate or multiply. They flourish and they obtain energy by the oxidation of dissolved iron in the water from the ferrous to the ferric state. The ferric form is precipitated as ferric hydroxide (Fe(OH)3).

When the temperature rises in their environment, like what happens to the water sitting overnight in the toilet tank rising to room temperature, or if air or oxidants are added to their environment, they tend to grow much faster and in greater quantities. What you are seeing in your toilet tank is the result of the iron bacteria converting soluble iron, from a liquid state (Fe2+), to the insoluble form, (tiny rusty flecks), many times referred to as "red water" (ferric iron (Fe3+)). It is in this stage that iron, and manganese, become deposited on the outside of the bacteria cell sheaths and the slimes they produce.

PLEASE, don't be afraid of the water! As mentioned earlier in this article, the bacteria are not harmful, they just look bad and sometimes add an iron taste to your water. Many persons have just come to accept them as part of the Alaskan way of life, as they truly are, pesky little microorganisms. Yes, there are ways to remove them from your well water and keep them from staining your clothes and fixtures, but that is another subject and will be explained in a separate article.

Getting back on track, the bacteria cell sheaths and slimes become encrusted with iron and manganese and it is then that you begin seeing the prominent red-orange color. This bacteria is the cause of various clogging and fouling problems with sand filters, iron filters, water softeners, pumps, even the piping. In a water treatment plant these bacteria can and do interfere with the filtration process and can also cause problems in the distribution systems. In this picture you can see how heavily encrusted the bacteria has become on this diffuser-blade assembly in about weeks time, and this is with 1000 cubic feet of air per minute rushing past this assembly 24 hours a day.

At the UAF water treatment plant, aeration and oxidation are the first step in our treatment process. This is where we can begin the process of removing the majority of these little nuisance organisms from the raw water entering the water plant for treatment.

Because these bacteria can cause taste and odor problems, frothing or foaming problems, can foul or plug dishwashers, washing machines, toilets, tubs and stain clothing, sinks and tubs, we work diligently to remove every trace of these bacteria before the water ever leaves the final filtration process of the water treatment plant. Any of the "rusty" or "dirty" looking water that does occasionally come out of the faucets and taps on campus is caused by other problems occurring in the distribution mains, as well as the "Taste and color" problems you experience on campus.

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