Water Hardness Salts
These salts are composed of Calcium, Magnesium and Potassium Carbonate, Nitrate and Sulphate, which dissolve in the water on its passage through the countryside before it reaches the reservoirs. (In the Transvaal for example, it is not unusual to find 300 ppm hardness as measured in Calcium Carbonate).
Soap is sensitive to water hardness as observed by the scum formed when washing in hard water, forming the “ring” in the bath and basin. This scum is sticky and readily attaches itself to fabric, discolouring it and turning it grey, thereby masking the original colour.
Detergents are also affected by hard water, producing a sediment which can be deposited on the fabric, necessitating the use of higher detergent usage levels to compensate. Unless the higher detergent quantity is used, or alternatively a water softening plant incorporated, not all soiling will be removed and deposits will mask the colour of the towel, or white towels can become grey in shade.