One of the renewable energy technologies for producing electricity from moving water is the Savonius turbine. This paper optimizes the Savonius turbine performance by conducting several CFD simulations and utilizing the mixed-level Taguchi method. The quality function was first created, and then the levels and factors were determined. After analyzing the mesh and the boundary conditions, the orthogonal array was built and the CFD simulation was executed for each run. The diameter is the parameter that has the greatest influence on the hydrodynamic performance, according to the Taguchi analysis, which demonstrated the optimal combinations of the parameters in low-speed streams. The main finding was that the modified water turbine’s power of coefficient (Cp) had a 15% improvement over the original design.