Hard Water

Clark's method is used to remove temporary hardness of water. Temporary hardness is caused by the presence of dissolved bicarbonates of calcium and magnesium, which can be removed by heating the water. When heated, the bicarbonates decompose to form insoluble carbonates, which precipitate out of the water. Clark's method involves adding slaked lime (Ca(OH) ) to the water to convert these bicarbonates into carbonates.