Hardness in drinking water is mainly the result of the presence of large amounts of two minerals - calcium and magnesium.
- Hard water requires more soap than soft water to obtain a lather.
- It can also cause scale to form on hot water pipes and fittings.
Soft water contains small amounts of calcium and magnesium.
It may lead to greater corrosion of pipes, although this will depend on other factors such as pH, alkalinity and dissolved oxygen concentration.
Drinking water in the Sunshine Coast and Noosa regions is generally soft (less than100mg/L), whereas in the Moreton Bay region it is neither hard nor soft (less than 200 mg/L).
Useful things to know in relation to soft water:
- Leave your water-using appliances on factory settings
- You do not need to add salt to the water
- If a dishwasher supplier quotes results in mmol/L, then 1mmol/L = 100mg/L
Degrees of hardness
Degrees of hardness are described in the Australian Drinking Water Guidelines 2011 as:
||Description of hardness
|Less than 60 mg/ L CaCO3 (Calcium Carbonate)
||Soft but possibly corrosive
|60-200 mg/L CaCO3
|200-500 mg/L CaCO3
||Hard, with increasing scaling problems
|Greater than 500 mg/L CaCO3
||Hard with severe scaling