Sediment erosion-corrosion is a critical threat to the safe operation of hydro turbines, which may lead to component damage or even complete failure of the turbine. A lack of understanding of the mechanism of sand erosion is a barrier to developing an erosion model to exactly quantify sand erosion in the Pelton turbine. The preeminent objectives of this research work are to determine parameters that influence sand erosion, identify erosion-prone areas in Pelton turbine buckets, quantify the erosive wear experimentally and numerically, determine the impact of erosive wear, and analyze the microscopic mechanism of erosion. Five Pelton buckets made of aluminum, carbon steel, stainless steel, polylactic acid (PLA), and acrylonitrile butadiene styrene (ABS) were used to perform erosion experiments under two-phase, solid-liquid flow conditions. Multi-layer paint modelling technique was used to identify erosion-prone areas. Optical profilometry was used to perform surface roughness analysis and Scanning Electron Microscopy was used to evaluate the microscopic degree of damage due to erosive wear in the Pelton bucket. Mass loss and thickness reduction analyses were performed to quantify the erosive wear. The erosion rates of aluminum, carbon steel, stainless steel, and ABS were 190 , 86.73 , 48.79 , and 5.61 higher, respectively, compared to PLA and both PLA and ABS demonstrated exceptional resistance. © 2023 Elsevier Ltd