Waterjet cutting operates by injecting water at high pressure together with abrasive material known as garnet to corrode the base material in the cutting process. The mixture of water, garnet and residue of corroded material is accumulated in the accumulation tank. The current practice in waterjet cutting industries do not recycle spent garnet and normally disposed in the landfill or mixed with cement in concrete for construction purpose. Hence, this research aims to investigate the optimum suction head for the recycling system of the spent garnet. The development of suction head in the recycling system is crucial to ensure the separation of spent abrasive garnet with material residue in forms of sludge. A closed-loop continuous flow filtering system is developed featuring venturi type sludge suction pump and multi-stage filters/separation. The venturi suction is connected to a primary pump and the secondary pump is attached at the other's end of the extraction flow. Findings show the highest extraction at 1.4833 liters per second of the spent garnet was achieved when the primary pump pressure is constant at 100 bar and secondary pump at 125 bar. Therefore, future works on a more comprehensive study can be conducted by deploying the significant results for field-testing in an industrial waterjet cutting.