Performance of permeable reactive barriers for contaminated groundwater remediation was evaluated using FEM seepage analysis. The retention time and the capture width were calculated on the funnel-and-gate system having different geometries, in order to evaluate the effects of these geometries on the performance of funnel-and-gate system. Based on the calculated results, costs associated with the installation of funnel-and-gate system satisfying a certain performance were obtained to estimate the cost-effective geometry. Finally, optimum design flow for permeable reactive barriers was proposed.