The paper presents the analysis of the geo-ecological state of groundwater within an urban territory on the example of Saint Petersburg. The paper considers two key sites, characterized by different levels of contamination of the underground environment (Primorsky and Krasnogvardeisky districts of Saint Petersburg) and provides an assessment of the main natural and man-made sources of the groundwater contamination within the territory of the selected districts. The composition of groundwater was studied in the zones with different pattern of contamination (cemeteries, liquidated landfills, industrial areas, etc.). The negative impact of the man-made sources of contamination on the state of groundwater was determined. The recommendations for arranging hydrogeological groundwater monitoring in metropolitan areas were developed.