Disinfection plays a great role in preserving health safety of water for human consumption. Subjecting water for human consumption to disinfection by certain chemical compounds such as chlorine mixtures, removes pathogenic microorganisms which can cause a plethora of contagious diseases. Usage of chlorine varieties such as gaseous chlorine, sodium hypochlorite (NaOCl) and chlorine dioxide (ClO2) can lead to production of different chemical byproducts such as trihalomethanes (THM), chlorates and chlorides; whose limit values are legally prescribed in ''Regulation on compliance parameters and methods of analysis of water for human consumption'' (NN 125/2017). Previously mentioned byproducts can have a negative effect to human health, if found in large concentration in drinking water, especially if the water has been exposed to it for a longer period of time. Although they can be very harmful for human health, even more detrimental are pathogenic microorganisms found in water, which makes the significance of disinfection even more relevant. The aim of this paper is to present values of physicochemical and microbiological parameters, obtained by laboratory analysis conducted on collected samples of water from four water systems of island Krk; as well as determine their drinking quality. Analysis was conducted by laboratory technicians of Ponikva laboratory in compliance with ISO standards, and processed data was collected in the period from 1st January 2018 to 31st December 2018. Moreover, the goal is to present the various ways of disinfecting water on island Krk, which are: disinfection by UV radiation in combination with chlorine dioxide, as well as disinfection by sodium hypochlorite, and compare the two.