In the article a investigation of the various pheno ena which influence to the drainage geocomposite efficiency used on a surface of the underground rigid basements is presented. The one geocomposite type was selected and tested. The long-time tests of the thickness and permeability with the different pressure were carried out. Influence of the soil pressure distribution, direction and velocity of groundwater flow, changes of the thickness and degree of saturation of the drainage system on its efficiency are determined.