The paper concerns the problem of possible contamination, which can be dangerous to the ground and surface water, because of an inappropriate localization and protection from leaching of harmful substances. The tests were carried out on a closed municipal landfill site in Chełmek, located in the west part of Małopolska Province. Issues concerning water circulation through the cells and landfill ground were analyzed. Using Giryński's field method a permeability coefficient was determined for wastes and ground soil. Granulation, compaction degree, bulk density and natural moisture content were also determined. Based on the obtained results a maximum distance of migration of harmful substances with a wide range of viscosity was calculated.While analyzing the results it was stated that the landfill is located too close to the Przemsza river. In case of an insufficient ground sealing there is a risk of leaching of harmful substances from the landfill and fine sands that are in the ground are not a sufficient barrier to contamination migration that will happen along with the ground water. ...