Hard water is a term that denotes water having very high mineral content.
Soft water can be defined as surface water that contains relatively low ion concentrations and is low in calcium and magnesium ions in particular.
There are various methods to remove the hardness of the water. Here will read about Clark’ method.
Clark’s method to remove the hardness of water
In Clark’s water softening method, hard water is treated with Ca(OH)2 (slaked lime). Calcium hydroxide is Clark’s reagent. It removes the hardness of water by converting bicarbonates into carbonate. Water softening by Clarke’s process uses calcium hydroxide (lime). It removes temporary hardness.
This method involves the addition of slaked lime to water either in solid or in liquid form. This results in the conversion of soluble bicarbonates to insoluble carbonates.