A Simple test to estimate the permeability of concrete is described. Movement of water under gravity through a 12.5 x 10 mm (0.5 x0.4 in) disk of concrete is monitored at atmospheric presure. Steady-state conditions are reached typically in 7 to 14 days, and values of permeability can be determined reliably in 14 to 20 days. The reproducubility of the test is satisfactory, and preliminary measurements indicate that it can discriminate between concretes that have been subjected to different curing conditions or excessive loads.