This standard specifies a method for the determination of water permeability under pressure in hardened concrete. It is applicable to both molded specimens and control specimens. It should be taken into account that the water permeability of concrete structures is strongly influenced by e! degree of compaction, the presence of joints, cracks or heterogeneities, as well as the way of conservation. For special applications in structures, pressures and test programs other than those specified in chapter 6 of this standard may be used. The method is applicable, in particular, to concretes with high permeability.