Relevance. By the beginning of the XXI century, the growth of cities, population concentration and the revival of industrial production led to an intense technogenic pressure on the underground hydrosphere. In ecological and hydrogeological studies, it becomes necessary to conduct monitoring observations of groundwater based on GIS technologies. Purpose of the work: study of the hydrogeochemical characteristics of underground waters of the aquiferous lower Kazanian carbonate-terrigenous complex to provide Kazan with high-quality drinking water from protected underground sources. Research methodology. Hydrochemical data from geological reports and archival materials for the period from 1960 years to 2019 years were used. Methods of mathematical statistics (basic, cluster and factor analyzes) made it possible to differentiate into natural and man-made components. Geographic information modeling using the “ArcGisMap” package showed the spatial variability of the main components in the waters of the Neogene complex at the turn of the 20th and 21st centuries. Conclusion. The hydrochemical parameters of the aquiferous lower Kazanian complex are assessed as favorable, since practically all the main components do not exceed the MPC values for drinking water.