The study included water samples from 10 test points located in the northern parts of Sanok and Lesko counties. The following analytical methods have been used: AAS (FAAS, CVAAS, HGAAS), ICP-MS, ICP-OES, Ion chromatography, Acid-base titration, argentometry, turbidimetry and also bacteriological tests. Two sources were identified as "natural mineral hard medium-mineralised waters" with low iron content. Four sulphide springs have been found. The Lesko source can be characterized as "a specific therapeutic sulphide water" with a content of divalent sulphur, determined iodometrically, above 1 mg • dm-3 and without any bacteriological concerns. Water from Lesko, apart from small amounts of metaboric and orthosilicic acid, is slightly alkaline with a strong negative ORP potential (-230 mV), which makes it healthy (an antioxidant that eliminates free radicals). In all waters the presence of heavy metals, arsenic, lithium, iron, manganese, alkali metals and alkaline earth metals has been indicated. The influence on the human body of analytically marked substances has been described.