0 Temporary Hardness:
The presence of bi-carbonate salts of calcium, magnesium and iron makes the water temporary hard. Temporary hardness of water can be removed easily by simply boiling the water. When the water is boiled, the bi-carbonates decompose with the liberation of CO2 and insoluble carbonates deposits as precipitation under water.
Ca (HCO3)2 → CaCO3 ↓ + CO2 + H2O
0 Permanent Hardness:
Permanent hardness arises when water contains soluble salts of calcium and magnesium such as their sulphates and chlorides. Permanent hardness is hardness (mineral content) that cannot be removed by boiling. Permanent hardness can be removed by converting the sulphate salts into carbonates with the help of soda ash (Na2CO3).
CaSO4 + Na2CO3 → Na2SO4 + CaCO3
Permanent hardness can also be removed with using a water softener or ion exchange column, where the calcium and magnesium ions are exchanged with the sodium ions in the column.
