Hardness is caused predominantly by Calcium and Magnesium salts in the water. The presence of these salts is generally naturally occurring. Hard water may cause scaling issues, problems such as soap not lathering, blocked shower roses, blackened aluminium cooking utensils and/or white deposits on your sink or inside your dishwasher.

Problems experienced due to new cement lined water mains occur mainly in new subdivisions where mains have been recently laid. Under these circumstances, the problem is generally only temporary until the pipes stabilise.

Most water supplied to Western Water customers has very low hardness. Some customers, such as those supplied by bore water or receivng water from new cement- lined water mains may have hard water.

Sometimes we receive enquiries from customers about the hardness of their water supply, when they purchase a new dishwasher. Instruction manuals provided with new dishwashers usually highlight water hardness as an issue requiring attention. However, user manuals may express hardness levels in units other than milligrams per litre (mg/L), such as millimoles (mmol) or parts per million (ppm).

Use the following equation to convert milligrams per litre to millimoles:


Hardness Equation: mg/L - mmol/L

For more information about water hardness please contact Western Water's
Water Quality Team on 03 9218 5400, during normal business hours.