What is the Difference Between Temporary and Permanent Hardness of Water?

The difference between temporary and permanent hardness of water lies in the types of minerals that cause the hardness and the methods required to remove them.

Temporary Hardness:

• Caused by the presence of bicarbonates of calcium and magnesium (Ca(HCO3)2 and Mg(HCO3)2).
• Can be removed by simple boiling and filtering the water.
• Also called carbonate hardness.

Permanent Hardness:

• Caused by the presence of chlorides and sulfates of calcium and magnesium (CaCl2, CaSO4, MgCl2, and MgSO4).
• Cannot be easily removed by simple boiling and filtering the water.
• Also called non-carbonate hardness.

Temporary hardness can be removed by boiling water, as the soluble salts of Mg(HCO3)2 are converted to Mg(OH)2, which is insoluble and gets precipitated and removed through filtration. On the other hand, permanent hardness cannot be removed by boiling and requires additional treatment methods, such as the addition of washing soda, Gan's permutit method, or Calgon's process.

Comparative Table: Temporary vs Permanent Hardness of Water

The difference between temporary and permanent hardness of water lies in their composition and removal methods. Here is a table comparing the two:

Temporary hardness is caused by the presence of bicarbonates of calcium and magnesium, which can be easily removed by boiling and filtering the water. On the other hand, permanent hardness is caused by sulfates or chlorides of calcium and magnesium, which cannot be removed by simple boiling and filtering. To remove permanent hardness, one can use an ion-exchange column or a water softener.