The thesis focuses on the characteristics of the area Spania Dolina with the emphasis on the impact of mining activities and the quality of water of grants, through the selected physicochemical, microscopic and cultivation methods. The aim was to identify and analyze the significant ecological and hygienic groups of bacteries (coliform bacteria, enterococci and cultivable bacteria at 22 ºC).We rated the quality of water on the basis of measured values and according to the regulation of The Slovak Government No. 354/2006 of the Codex. This codex lays down the requirements for water intended for the human consumption. According to the results of the selected microbiological indicators, was found out the appearance of the coliform bacteria. It indicates weak protection of water source, the lack of water treatment, its health insurance and secondary contamination. According to government regulations No. 354/2006 of the Codex, was exceeded the limit in the delivery points Grant fire brigade 2 KTJ/100 ml and Grant on the main road 2 KTJ/100 ml , the limit was 0KTJ / 100 ml for the drinking water.Based on the results, it was found the appearance of enterococs, which are the indicators of fresh cesspit pollution. According to the government regulation No. 354/2006 of the Codex, the appearance of enterococs exceeded the limit 0 KTJ/100 ml for drinking water in samples taken from Grant at the cemetery 1KTJ / 100 ml and from Grant Pustô 1 KTJ/ 100ml. The appearance of cultivated bacteries at temperature 22 °C, which are the indicators of general water contamination, it didn´t exceed the limit 200 KTJ/ml in any sample. The limit was established by the Slovak Government regulation No: 354/2006 of the Codex. Appearance of ferric bacteries Leptothrix sp. and Gallionela proves the presence of the increased amound of Fe and Mn.