Drinking water disinfection is necessary in order to minimize multiplication of microorganisms in engineering water supply systems and to eliminate the possibility of human infection, which could lead not only to deterioration of the public health and working abilities but, consequently, to significant economic losses. This is a serious problem in developed countries and partially in Latvia too, as significant number of people consume low-quality water from individual wells and have no access to the centralized water supply systems [1]. By improving microbiologic quality of drinking water in de-centralized water supply systems, number of infections caused by poor water quality will be significantly decreased.