Photovoltaic water pumping systems is a practical alternative to traditional systems in remote areas. However, the efficiency of solar energy utilization heavily relies on the optimal design of the maximum power point tracking (MPPT) algorithm that can increase power extraction from PV panels. In this paper, a modified MPPT algorithm is proposed for driving a single-stage PV water pumping system with a three-phase induction motor (IM) driven by scalar V/f control technique. The proposed modified CSS-INC MPPT algorithm combines the benefits of two modes algorithm, the Confined Search Space (CSS) algorithm and the Incremental Conductance (INC) MPPT algorithm. The CSS algorithm is utilized to decrease the search area for the INC MPPT algorithm in tracking the maximum power point (MPP) of the P-V curve, resulting in improved and faster tracking capabilities. MATLAB simulation was conducted to evaluate the performance of the proposed CSS-INC MPPT algorithm, and the results were compared with the conventional INC MPPT algorithm under varying weather conditions. Simulation results demonstrated that the proposed modified MPPT algorithm achieves much better performance compared to the conventional INC MPPT algorithm where the modified MPPT algorithm can improve the efficiency and productivity of PV water pumping systems under varying weather conditions.