Abstract
A manual is presented which describes how vertical screens, made of loose granular material, inserted in a groove of more than a meter deep and not less than 15 cm wide, continuously constructed along both sides of a road, can prevent rainwater to enter from the verge under the road surface. Although the word capillary is used, the goal is to prevent capillary transport of water by disturbing the continuity of the soil The descriptions cover the problem, the design and construction of the screen and its maintenance. The screen must be covered on top to prevent it from acting as a drainage system.