Temporary hardness is due to the presence of bicarbonates of Ca and Mg. Temporary hardness can be removed by clarkes process which involves the addition of slaked lime. NaOCl+H2O ⇌ HOCl+NaOH Washing soda removes both the temporary and permanent hardness Ca(HCO3)2+Na2CO3→CaCO3↓+2NaHCO3