This unit has been designed for the practical demonstration, visualization and experimental study of the flow through permeable media and flows in subsoil. The unit basically consist of a tank (soils container) to contain the sand, lower water tanks, a pump for the water flow, pressure meters, a dye injection system with dye injection needles. The soils container consists on a rectangular tank, with back side in aluminium and front side in methacrylate to see the flow lines. It contains the wet sand which must be collected or sampled by the student. The sand distribution in the tank must be according to the experiment configuration which we want to carry out. For it, there are overflow pipes to be able to put them at different heights, and going up and down the tubes. The outlet tubes of the overflow pipes make easier the water falling to the tank which has a level switch and a key in order to the lower water tanks go out. The water flow can be measured. A set of typical models is included: a sheet pile wall, 2 mesh gates and a mobile accessory for pressure measurement, for pressure fall measurements tests, phreatic layer tests, earth dam, etc. To check the flow lines, there is a dye injection system. This system has a dye vessel and injection needles through where the liquid flows and which are inserted in the sand in the tank, close to the methacrylate side for the flow visualization lines.