Variability of Drinking Water Quality on the Basis of Analysis of Qualitative Monitoring from a Selected Water Supply Network Located in South-Eastern Poland

Various groups of contaminants can be found in water intended for human consumption, such as bacteria, viruses, chemicals, and heavy metals. Many of these contaminants can cause serious health problems, so it is extremely important to ensure that water quality meets current standards. The main objective of this study was to analyze and evaluate the variability of drinking water quality in a selected water supply system located in the southern part of Poland. The results of the research and analysis presented in the study were prepared on the basis of test reports carried out by the water supply company during the operating years 2018–2022. A total of 28 indicators from the group of physicochemical and microbiological parameters were analyzed: color, turbidity, pH, electrical conductivity, nitrates, nitrites, chlorides, chromium, aluminum, cadmium, magnesium, manganese, copper, nickel, lead, mercury, sulfates, total iron, oxidizability, chloroform, total THM (Trihalomethanes), total organic carbon, chlorites and chlorates, Escherichia coli, Enterococci, Coliform Bacteria, Clostridium perfringens (with spores), and total hardness. The results obtained were compared with national and European standards. The analyzed tap water was characterized by a stable physicochemical composition and did not exceed microbiological parameters. The only parameter that would not meet the acceptable value is chromium. Its value in each of the analyzed months was <3.0 μg/L, while the new directive tightens the requirements to 0.25 μg/L. The water supply network operator should take action to reduce the amount of chromium in tap water so that it follows the introduction of new regulations on the quality of drinking water.