The permeability of cement mortar is of pivotal significance in structures which are intended to retain water or those which come into contact with water. Besides functional considerations, permeability is intimately related to structure durability.  Resistance to progressive deterioration under exposure to severe climate and bleaching due to prolonged seepage of water containing corrosive gases or minerals are solely dependent on durability. The determination of permeability characteristics of cement mortar, therefore, assume essential importance.