Typical sand trap flushing systems, such as Büchi and Dufour, require water volumes up to six times the deposited sediment volume for efficient flushing. Furthermore, complete sediment removal particularly in Dufour sand traps can only be realized with drawdown flushing, resulting in operation time and water loss. The objective of the described research project is to improve the flushing system of an existing Dufour sand trap. Numerical simulations, performed with two software packages ANSYS CFX and FLOW-3D, are carried out to investigate the flow dynamics in the flushing system and to investigate the required sediment flushing discharge. The flow in the existing flushing system is first studied to evaluate the actual performance of the system. Numerical simulations of the flow in the new flushing system, using the same sand trap, are performed to assess the induced improvements. A good agreement between the results of the numerical simulations using both software packages is observed. Regarding the velocity field in the flushing channel, the existing system is only efficient on the last third of the channel. In the new system, the velocity magnitude is sufficiently high all along the flushing conduit ensuring a good efficiency of the whole system.