Due to various problems that occur during treatment the water containing significant amounts of humus substances, using classical methods, the thesis on possibility to apply the hybrid system to its purification has been proposed. The purpose of the combination was to achieve higher efficiency as compared to component processes. Studies allowed for finding that combining filtration in a ground, preliminary ozonization and reverse osmosis gives a possibility to get water of a constant quality, regardless the indices oscillations, to avoid products of humus substances degradation and to protect membranes against fouling. During initial stages of RO process, strong weakening of filtrate stream is observed, and then it is stabilized at constant level with subsequent decreasing after some time. Achieving a maximum efficiency is associated with finding the reason of permeate stream weakening during water treatment. ...