The study of invertebrates in water supply systems is important because it provides insight into the problems caused by their occurrence in drinking water. Their origin and survival in such a system is a significant aesthetic and health problem. Some invertebrates successfully survive the process of groundwater and surface water treatment. They are able to colonize certain parts of the technological process of drinking water treatment, clean water tanks and water supply systems. In this way, their presence in treated drinking water often occurs. Specifically, the dominant species of invertebrates in drinking water distribution systems are mainly cosmopolitan and eurivalent species, biological vectors that are carriers of agents of different diseases (viruses, bacteria, protozoa and other invertebrates). It is known that the presence and survival of invertebrates in drinking water distribution systems are in positive correlation with the concentration of organic detritus and biofilm in such a system. However, such an extensive research in water supply systems in our country have not bin implemented yet, the goal of the proposed research has bin identifying the presence of invertebrates in drinking water distribution systems in eastern Croatia, using statistical analyzes to determine whether the physicochemical parameters of water for human consumption correlate with the abundance of invertebrates. Furthermore, the aim is to develop effective procedures for their removal using: chlorine, chlorine dioxide and ozone. Through research, it has been proven that different taxonomic groups of invertebrates colonized the investigated water supply systems. We also found that physicochemical parameters significantly affect their survival in the water supply system. It came to the results of what disinfectant concentrations are required for successful inactivation and removal from water supply systems.