The assessment of the individual elements of the water balance in the catchment area of a small river was made. The water balance equation of Bodrak Basin (north-western slopes of the Crimean Mountains) based on hydro-chemical data was proposed. When calculating the incoming articles of precipitation the authors used data of the weather station located in the village Pochtovie. The corrections to the vertical zoning were inputted when calculating. Estimation of the condensation flow was based on long-term observations of the karst spring during the low-flow period. Estimations of evaporation were based on the calculation methods, recommended in the special publications. Refs 19. Figs 3.