Well water in Western Ireland is commonly contaminated with excessive amounts of iron and manganese. These substances cause brown rust stains or black stains in sinks and laundry. Often the drinking water has an unpleasant taste and odour.

High levels of iron and manganese may not be apparent when water is first poured into a glass but after a period of time the water will go from becoming clear to having a slight or strong brownish red colour. This occurs when air reacts with dissolved ferrous iron in the water causing it to oxidise forming ferric iron. The iron and manganese will eventually settle to the bottom of the glass.

Ferric iron, which is insoluble in water, will give the water a brownish red colour as soon as the water leaves the tap because it has already oxidized in the plumbing pipes or in the well.

Most water treatment authorities do not consider the presence of iron or manganese in the water to be a health risk; however, for aesthetic reasons and in order to reduce the staining of laundry, appliances and sinks, and to improve the taste of water, an EU Directive states that maximum admissable levels of iron should be 0.2 parts per million and manganese should be limited to 0.05 parts per million in drinking water.

The procedure for reducing these substances in water can range from simple to complex. Other substances and varying factors concerning the water require that a proper water analysis and professional appraisal be carried out. At this point it is important to note that non-disinfected water samples should receive a microbiological laboratory analysis to determine that no harmful bacteria is present. It should not be assumed that water softeners alone or with silver impregnated carbon added to them or iron/manganese removal systems will make contaminated water safe to drink. Specific systems for harmful bacteria, which I discussed in a previous 2nd July issue of the Tribune, should be utilized.

A water softener is often installed to remove iron and manganese as well as limescale. In most circumstances it will greatly reduce low levels of iron and manganese but positive results must not always be assumed. Complicated conditions may exist causing the water softener to appear to be working properly but within days or weeks, iron and manganese staining will re-appear and hardness levels of treated water will rise. Under these conditions the home owner would have originally required a specialized iron/manganese removal system installed on the mains to treat the water before it enters the water softener.

The most common types of iron and manganese removal systems found in Western Ireland are ones that utilize oxidizing agents such as air, potassium permanganate or the chemical chlorine to oxidize ferrous iron into its insoluble and visible ferric state. Various types of final filters are then employed to remove the resulting ferric iron, any remaining colour as well as other objectionable substances and to improve the taste of the water.

The decision as to which water treatment system to install will be determined by a professional water analysis appraisal, projected level of efficiency, maintenance requirements and maintenance costs. These factors vary and should be considered for each individual application. Home owners who have non-disinfected water or suspect water conditions, should always ask for a microbiological laboratory analysis as part of their water test and any purchase agreement or exchange of payment should be based on a satisfactory demonstration of performance once the appropriate equipment is installed.