ABSTRACT: The groundwater monitoring of contaminated sites carries an extensive database, which is currently processed in accordance with applicable legislation and methodological guidelines. However, the potentiality of the obtained hydrogeological data is not fully utilized. Additional methodological approaches representing a combination of hydrogeochemical, and multivariate statistical methods offer a promising complementary tool, which not only speeds up the data evaluation itself, but can also point out or reveal hidden features of the monitored area. The hydrogeochemical data from contaminated sites of Predajná 1 and Predajná 2 were processed using geochemical modelling, hierarchical cluster analyses, and principal component analysis. Results indicated both inorganic and organic pollution at the study site. The inorganic pollution was evidenced by high values of TDS, natrium, Chlorides, and sulphates, while organic pollution was represented by TOC and surfactants. The outcomes of the methodology used at the study areas revealed zones in which the degradation processes of organic matter or the reduction of iron and manganese took place.