This paper reports on the water resistance of single leaf and diaphragm masonry walls as measured by the standard ASTM water permeance test. The effectiveness of two types of clear water repellant coatings is also considered. Since the standard test does not simulate practical weather conditions a criterion for satisfactory performance of a wall is derived. This criterion is in terms of the standard test result and a monthly driving rain index obtained from weather records at the wall location. It is concluded that more data are required to reliably establish the relationship.