Comparative results of chemical composition and water salinity in Shostka town are given for the periods of 1967-1970, 1971-1980, 1997-2000, 2001-2005, 2006-2010, 2011-2013. Over the same periods, the article presents the results of environmental assessment of water quality on criteria of components of the salt content pollution, environmental sanitation indexes and content of specific substances toxic effects. Index of water pollution was calculated and the overall assessment of pollution was made by the whole set of indicators. Key words: water, chemical composition, salinity, assessment, pollution, heavy metals, elements.