Hardness of water majorly shows the concentration of Calcium and Magnesium salts dissolved in it which do not allow the lathering of soap and thus not good for washing or skin.
Carbonate and bicarbonate salts are generally categorized under temporary hardness whereas permanent hardness includes sulphites, nitrites and other metallic salts.
The temporary hardness can be removed by ion exchange resin method by replacing Ca and Mg ions with Na (sodium) ions. The process is proven, safe and chemical free for the use in industry.
This makes the water soft and the lather formation with soap is excellent so is the cleaning.
But soft water is not recommended to be used for drinking purpose due to the lack of Ca, Mg salts which are required by the human body.