The thesis produces a risk assessment of supplying drinking water. It focuses on a water supply system in the area of the Trnovo Forest. The building history of the forest is specially interesting, since it has been built with the help of 4 countries. The drinking water supply in this system is entirely dependent on the performance of the penstock route from the Skuk reservoir to the water storage Predmeja.Therefore, the risk assessment was made primarily on the penstock route area. Based on the distribution of the water supply system into different subsystems, building blocks and components, it is possible to create a register of risks, the purpose of which is to assist the operator in determining the measures and actions to improve performance and reduce risk. The method used for risk assessment in the water supply system Gora has allowed a good identification of risks for various hazardous events that could endanger the operation of the water supply system.Based on the produced risk register, the creation of preventive measures, that would contribute to greater operation safety of the water supply system, is possible. All results of the risk assessment were produced with the help of the operator of the water supply system.