Adsorbable organic halogens (AOX) are sum parameter can be determined in surface waters, drinking water and waste water as well as in soil and leachate from landfills. Although the presence of AOX in waters is of anthropogenic origin, they may also be of natural origin. In water environments they have long half-life, they resist breaking down and can accumulate in the food chain. Some of the compounds that are ranked among the AOX, are carcinogenic, mutagenic and teratogenic at high concentrations.Threshold values of AOX's in drinking water are not detemined by Slovenian legislation. First measurements of AOX concentrations in drinking water were made in 2014, in areas where water supply system is
managed by Hydrovod d.o.o., Komunala Brežice d.o.o., Komunala Črnomelj d.o.o., Komunala Metlika d.o.o., Komunala Novo mesto d.o.o. in Kostak d.d. The Master thesis gives an overview of the concentrations of AOX in surface, groundwater, potable water and in industrial wastewater in the Dolenjska and Bela Krajina regions between 2000 and 2014. Based on the data obtained, it was found that the concentrations of AOX in drinking water in
the area of Ribnica, Kočevje and Sodražica water supply systems (karst surface of mesozoic limestone and dolomite), were higher than at other measuring sites. Moreover, concentrations of AOX in drinking waters treated with chlorine compounds were higher than in raw water. Concentrations of AOX in surface waters were mostly suitable and status of surface water bodies was identified as good. It was also found that in most plants the annual quantity of AOX in technological wastewaters exceeds the threshold for waste waters.