Artificial groundwater recharge of aquifers by percolating water through the unsaturated zone (UZ) is a technique to enhance the water quality for drinking, irrigation and industrial water supplies. The performance of the UZ to purify the infiltrated water is based on both chemical and hydrodynamic properties of the porous medium. The chemical and microbially mediated redox-reactions involving the degradation of organic substances are the key phenomena controlling the efficiency of such process allow developing filtrating and reactive zones beneath an artificial recharge system. For several decades, BRGM develops research and industrial projects to support the development of this technology and its implementation in various climate, soil, industrials contexts and specific use of water. A part of obtained results highlighting several physicochemical phenomena potentially favourable to the creation of pollutant filtrating reactive redox zones will be presented. This study has confirmed the interest of the unsaturated zone in water purification process.