The topic of this final paper is the application of air valves in the water supply pipeline, which are used as an essential hydromechanical tool for preventing the negative effects of air in the pipeline. The causes of air in the pipeline are multiple: existing air in the pipeline before the initial filling of the pipeline with water, dissolved air in the water, air entering the pipeline during the operation of the pipeline by unwanted suction from the environment. In order to better understand how to effectively manage the air in the pipeline, it is important to know the general flow characteristics of the two-phase mixture of water and air in the pipeline, which is briefly described in the paper. Air as an occurrence in pipeline systems can cause many problems in pipeline functioning, such as reduced flow capacity, increased electricity consumption, vibration, cavitation, etc. Air valves are one of the most economical and efficient solutions for air management in water supply pipelines. This paper describes three different types of air valves and their functioning in a piping system. For the air valves and pipelines to function effectively, proper selection, sizing, and positioning of the valves must be performed. Valve sizing and positioning is a time-consuming task, and computer software solutions are increasingly being used. In the practical example of the water supply branch of the Bodulovo Entrepreneurial Zone in Rijeka, the usage of the ARIavCAD air valves sizing and positioning program by A.R.I. from Israel is shown.