Abstract— Hydropower is one of the best renewable energy sources in Indonesia because they (hydro and micro-hydro) have large potential resources and suitable with water zone topology of a country with many rivers and similar water source. However, the percentage of installations Hydropower in Indonesia is 11.95% which is quite large considering the overall value of the investment. To optimize the water resources, development is needed in terms of hydro-electric power, which one of the well alternatives is the development of the water turbine rotor design. This study aims to determine the effect of adding stages on the performance of the savonius water turbine on the horizontal axis. The research subject will use a one-stage rotor that will be modified into two-stage. Variations in the shift angle are applied at an angle of 90° and the speed of water is 0.8 m/s and at TSR interval of 0.4-0.9. Simulation using Transient Blade Row type analysis. The calculation of the research was carried out using the computational fluid dynamic technique of the ANSYS codes in which the interacting fluid flow and turbine structure are explicitly modeled. Results data present torque distribution, velocity streamline, and coefficient of power (Cp). The tendency indicated that Cp was achieved in Savonius with the modified double-stage rotors. This configuration is suitable for an urban water source, such as sewage water pipes, which is capable to optimally utilize the flow of wastewater as a new energy resource. Furthermore, the emissions level due to machine combustion using fossil resources can be reduced.