Prevention of secondary pollution of drinking water in water supply networks made of metals

Introduction. The requirements of current regulatory documents guarantee the quality of drinking water leaving water treatment facilities (WTF). Hence, the water, coming into water supply networks, made of steel and cast iron pipes, made of gray-cast iron, is transported to consumers. Its quality must meet the standards of GOST R (Russian National Standard) 51232-98 “Drinking water” and SanPiN (Sanitary Regulations and Norms) 1.2.3685-21 “Hygienic standards and requirements to ensure the safety and (or) harmlessness of habitat factors for people”. The aim of the study is to analyze methods of preventing secondary pollution of drinking water in water supply networks, made of metal, and to identify the most effective and practically grounded method. Materials and methods. The concepts of electrochemical corrosion and microbiological corrosion of the inner surface of pipes were used to perform the analysis. Three methods of preventing the formation of a layer of deposits on the inner surface of steel and gray cast-iron pipes are used in the practice of water treatment and disinfection of drinking water: the method of using strong oxidants, such as chlorine and sodium hypochlorite, for the disinfection of drinking water; the method of increasing the pH level of drinking water; the method of using chemicals to ensure the formation of a microscopic film on the surface of layers of deposits to “slow down” electrochemical and microbiological corrosion processes on the inner surface of pipes. Results. The authors have identified a method for preventing the secondary pollution of drinking water, time-tested by the twelve years of practical use by the operator of WTF and drinking water supply and distribution networks made of metal. Conclusions. The effectiveness of the method of preventing the secondary pollution of drinking water through the use of new generation reagents, made of polyhexamethyleneguanidine hydrochloride, has been proven in practice.