The purpose of this work was to examine the influence of the structure of the porous layers, as well as the surface velocity of the fluid flow on the values of the pressure drop in the system. The pressure drop is a direct consequence of the resistance that appears during the fluid flow through a specific porous layer. Due to the significant influence of the structure of the layer on the hydrodynamic conditions within it, a detailed characterization of the three examined layers was carried out. For the quantitative description, easily measurable quantities were used, thus indirectly obtaining certain characteristics of the layer. It was experimentally observed that by increasing the height of the porous layer, the pressure drop in the system increases significantly. At lower values of surface fluid flow velocities (v a < 0,019 m s -1 ), the pressure drop increases linearly with increasing height, while for higher values of v a , this increase is exponential. It was also observed that an increase in surface flow velocity, at a constant height of the porous layer, causes an increase in energy losses. The value of the pressure drop through the porous layer in that case increases exponentially with increasing v a . By comparing the experimentally obtained pressure drop values for the examined porous layers with the values determined by theoretical equations, it is observed that the deviations are the smallest when using the Ergun and/or Burke- Plummer equation, but for a more reliable conclusion, it is suggested to conduct further identical tests in which the porous layers would be included a larger range of particle sizes.