In the paper, there were presented the possibilities of applying multidimensional methods to analyse the quality of drinking water. Based on the three year research results (2009 – 2011), analyzed were the physical and chemical parameters of drinking water from 15 water supply systems in the district (in Polish: powiat) of Łosice. Groundwater supplied by all the systems was of good quality as, during the period studied, only 7 cases were reported where the content of iron was exceeded, 2 cases where the colour level was exceeded, and 1 case with the exceeded level of KMnO₄ oxidation. The principal component analysis (PCA) showed that the parameters associated with the first four components impacted the quality of water analyzed most of all. The cluster analysis made it possible to distinguish 4 groups of water supply systems, which differed as regards the quality of water supplied. Group I comprised the systems with hard water and, at the same time, with low contents of iron and manganese. The water systems in group II supplied water with a low content of nitrates. The water in the systems of group III contained relatively high amounts of iron and manganese, but, at the same time, its hardness was the lowest and it was characterized by the lowest value of the electrical conductivity index. Group IV comprised the water supply systems that provided water with a relatively high turbidity level and a high content of iron; however, its pH value was very low.