Water hardness refers to the presence in water of calcium and magnesium, the origin of which is related to geological characteristics at the water’s source. Hard water, containing elevated levels of calcium and magnesium, causes difficulty in creating a soapy lather and forms crusty deposits (scale) in kettles, electric irons and washing machines. If the scale collects on heating elements it shortens their life and makes appliances less efficient.
Melbourne’s water supply has very low hardness and therefore can be regarded as quite soft. For example, Australian drinking water guidelines state that total hardness (expressed as calcium carbonate – CaCO3) should not exceed 200 mg/L (milligrams per litre), whereas the average water hardness level in City West Water’s area is approximately 22 mg/L (with maximum levels less than 30 mg/L).
On a fairly regular basis we receive enquiries from customers regarding the hardness of the water supply. These are mainly from customers who have recently purchased a new dishwasher. Instruction manuals provided with dishwashers usually mention water hardness as an issue requiring attention. However, the manuals may express hardness levels in units other than mg/L.