Rain water is naturally slightly acidic – this acidity causes it to dissolve chalk and / or metallic deposits present in the local rock strata which leads to the contamination of the water. This results in ground and borehole water containing a number of elements that would not otherwise be present in mains water. These contaminants (such as iron and manganese) can then cause problems when the water is put into use.
Acidic water results in the corrosion of pipework, heating cylinders and equipment and any iron and manganese present will result in poor tasting water in addition to staining baths, basins and any appliances with which the water may come into contact.
A pH value of below 7 is considered to be acidic – corrosion accelerates at pH levels below 6.5 with a level below 6.0 considered to be extremely aggressive. It is usually difficult to remove iron and manganese from acidic water so often the first step in the removal process is to raise the pH.