A theory is described which can be used in designing a vertical drainage system. This theory incorporates important parameters such as vertical discharge capacity, remoulding effects during installation and filter resistance. The importance of these parameters is widely recognized, but very seldom taken into account in the design, by engineers. Six well-documented case records, related to different drain types are briefly presented. Experience gained from these case records shows that in many cases, even if the overall performance appears successful, there are aspects of soil/drain behaviour that cannot be explained on the basis of existing theories. L'article decrit une theorie que l'on peut appliquer a la conception d'un systeme de drainage vertical. Cette theorie renferme d'importants parametres tels que la capacite de decharge verticale, les effets du remaniement pendant l'installation et la resistance de filtration. L'importance de ces parametres est reconnue par bien des ingenieurs, mais ils en tien...