a substantially steady state measurable flow of the aqueous medium into the concrete structure from the selected length of borehole measuring the steady state flow of aqueous medium and computing from the steady state flow measurement the water permeability of the concrete structure an apparatus employing the method is also disclosed application_number US 82181192 A description the invention provides an expedient and efficient method for the field measurement of the water permeability of concrete structures and a convenient easy to use portable apparatus for making the measurements referring to fig1 a cross sectional view of the apparatus of the invention is shown the apparatus consists of probe 10 which comprises a smooth metal preferably stainless steel rod 12 which is externally threaded at its distal 14 and proximal 16 ends to receive nuts 18 and 20 respectively expansible preferably neoprene packers 22 surround the rod 12 between the proximal 16 and distal 14 ends to define a test section 24 the rod 12 is hollow from the proximal end to adjacent the packer 22 nearest the distal end 14 within the test section 24 and between the packers 22 the rod 12 is provided with openings 26 to allow communication between the hollow interior portion of rod 12 and the test section 24 a central sleeve 28 perforated such that the perforations coincide with the opening 26 is positioned around the rod 12 between and communicating with the ends of the packers 22 in test section 24.