The relevance of the topic is conditioned by the need to ensure environmental safety of mining production in connection with the pollution of surface and groundwater. The main aim of the research is to study chemical composition of waters in technogenic reservoirs in the area of tungsten and molybdenum deposits; to detect the components groups characterized by abnormal content in waters; to consider the processes of technogenic waters purification on geochemical barriers and possibilities of their application in practice. The methods used in the study. Chemical-analytical studies were carried out by conventional methods: turbidimetry (SO4 2-), potentiometry (HCO3-, Cl-, F-), colorimetry (Si, P, NO3-, NH4+); cations and metals were determined by atomic absorption on the SOLAAR M6 spectrophotometer and mass spectrometry with inductively coupled plasma (ICP-MS) on the ELEMENT 2 device. The results. The author has studied the peculiarities of chemical composition of water formed within the areas of molybdenum and tungsten deposits in Eastern Transbaikalia. Significant differences in their physic-chemical characteristics are shown. The most mineralized acidic, sulphate water with maximum content of heavy metals were recorded in the waters of tailings from processing plants, in drainage water of waste rock dumps and in ponds-sumps. The author allocated the groups of elements of greatest danger for aquatic ecosystems: Cd, Cu, Zn, Th, Mn, Al - in acidic waters, W, U, As, Mn - in alkaline waters. Oxygen, alkaline and sorption types of permeable reactive barriers were investigated in the areas of deposits. The possibility of use of complex geochemical barriers, as well as aerobic and anaerobic wetlands for treating contaminated water was discussed.