Water losses in water supply and distribution systems are a big problem in Croatia and in the rest of the world. They cause large economic and environmental losses that could be reduced by correct management of the water supply system. Total water losses can be split on real (physical) and apparent (commercial) losses. Real losses occur due to water leakage in pipelines, storage overflows and by water leakage in the place in the pipeline before connection to the customer. Apparent losses occur due to unauthorized consumption, customer meter inaccuracies and systematic data handling errors. Main methods for lowering water losses, that are defined by IWA team for water losses, are pressure management, active leakage control, speedy and quality repairs and infrastructure management. By using these methods water losses can be lowered and that should be the goal for every system i.e. country because we are talking about public water supply systems. Average water losses in public water supply systems in Croatia are around 50% which is the average percentage in water supply systems around the world. European Union suggests that water losses should be bellow 15% which means Croatia has a lot of work to do to lower losses.