Changes in concns. of CI, S and NH4 ions as well as PhOH in groundwater flowing out from a region of chem. waste landfill located near Tarnow city, PL, were analyzed in 1998-2017 in accordance with the relevant stds. Purfn. of waters from the landfill in a sewage treatment plant as well as cessation of the storage of new waste resulted in improved purity of the analyzed waters.