Because of the excessive accumulation of zinc in the water system of one of the integrated steel plants, analysis of the said factor distribution in water circuits and final water treatment plant with different options of supply and desalting has been carried out. A method of computer simulation of salinity balance was utilized based on the previously developed software Visual Woda (VA (R)) adjusted to any model of water management system (serial, parallel or mixed). The scope of the system modification, aimed at improvement of circulating water quality and observing the required standards of sewage effluents.