The presence of dissolved magnesium and calcium salts causes hardness in water.
Hard water is a phrase that indicates water having a very high mineral content. As water percolates into deposits of calcareous, gypsum or chalk that are primarily comprised of carbonates of magnesium or calcium, bicarbonates and sulfates, hard water is formed.
Types of Hard water
Temporary Hardness of Water
The presence of magnesium and calcium carbonates in water makes it temporarily hard. In this case, the hardness in water can be removed by boiling the water.
Permanent Hardness of Water
When the soluble salts of magnesium and calcium are present in the form of chlorides and sulfides in water, we call it permanent hardness because this hardness cannot be removed by boiling.