A: Ground water usage for all purposes is increasing. Domestic garden bores are now common place and more ground water is being accessed by municipal water providers than ever before. The issues of ground water chemistry and more particularly dissolved iron and its effects continues to create confusion for many users of groundwater. During irrigation dissolved iron can be instrumental in causing various problems, such as brown - red stains on contact buildings, paths, roadways and plants. Additionally, under certain circumstances dissolved iron can cause blockages on the inside of the distribution pipes and down in the bore hole itself.

Cascading bores that contain appreciable amounts of iron are most noted for iron problems within the bore. Bores of this type are where water enters the bore hole outside the normal water column, or more simply the water tumbles down from the top of the bore hole and is exposed to air during its decent. These types of bores emit a ‘water fall’ sound when filling soon after the bore pump is stopped. As well as cascading bore types, water levels that vary during pumping can also contribute to iron problems both in and out of the bore hole.

Other problems with dissolved iron may be caused by the construction of the bore hole itself and can relate to the way the water enters the bore from the aquifer during pumping. Now more commonly iron impacts on pumping and irrigation systems when the water chemistry is altered by groups of colony forming micro-organisms called iron and/or sulphate reducing bacteria. These bacteria can cause large amounts of insoluble iron to be produced in the bore hole, pump and distribution lines.

Dissolved iron does not exist in all water bores at levels that cause problems. Most ground water contain some iron, but it is usually to small an amount to cause a problem. Iron concentrations are measured in milligrams per litre (mg/l). For example an iron concentration of greater than 1mg/l will usually become apparent during use. Iron concentrations of 5 - 6mg/l will leave no uncertainty about the existence of iron within your bore water.

Iron in ground water continues to represent serious problem for many irrigation systems, in particular micro-irrigation. The problems of premature wear and fouling of distribution systems by iron is just the beginning of the problem. High concentrations of iron in irrigation water can lead to illthrift with plants that come in contact with this water. Illthrift is caused by the red/black material (iron) accumulating on plant leaves and reducing the plant’s ability to perform the functions of photosynthesis, transpiration, and respiration.

Determining how iron will affect your water system can require a laboratory analysis and a qualified evaluation of the results. In many situations where iron exists alone in the bore hole water, the answers are not simple and solutions may not be within the bore hole itself, but may need the removal of iron by aeration and settling in a tank or other means.

Where bacteria are proven to be part of the problem then remedial work on the bore hole can be completed and equipment installed to give long term control. If the bore hole water contains even moderate levels of iron in the presence of bacteria, then simply controlling the bacteria in many cases will not control iron staining.

Biostat engineering can provide answers and solutions for iron related problems. Our new analytical department, comprised of a full time microbiologist, chemist and technical staff, will provide you with sample testing results. The Biostat Engineering team based in all Australian states can then provide you with the equipment you need to solve your iron bacterial problems.

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