This paper presents an analysis of the impact of geometric modifications of drilled impellers on the performance of low-speed centrifugal pumps. Drilled impellers, characterized by simplified design and operation at very low specific speeds, offer an alternative to conventional bladed impellers. Experimental tests were conducted for two impeller variants: a reference version (IMP1) and a modified variants (IMP2, IMP3), which included additional blind holes on the outer rotating surface. The objective was to increase the pump head without changing the outer diameter or rotational speed. The results showed that the modification in IMP2 led to a 17.9% increase in head for BEP (Best Efficiency Point) and relative increase of 12.5% for IMP3. Despite the reduction in efficiency, this solution may be beneficial in applications where achieving a high head is more critical than maintaining high efficiency. The findings indicate potential for further optimization in specialized pump applications using drilled impeller designs.