Alluvial aquifers are widely used as a groundwater source in many countries, mainly due to their high production potential, proximity to demand areas, their ease, and economy of extraction. By pumping wells located in an alluvial plain hydraulically connected to a river it is possible to generate a hydraulic gradient so that surface water is forced to flow through the bed and the banks of the river (Figure 1). During this process, known as riverbank filtration (RBF), a reduction in the concentration of pollutants is achieved by physical, chemical, and biological processes that take place, between the surface water and groundwater, and with the substrate.