Electrochemical technologies for wastewater treatment present several promising characteristics to be used as decentralized systems. In this work, synthetic grey water (SGW) was treated in a three-dimensional (3D), flow-through electrochemical reactor filled with granular activated carbon (GAC), which enabled simultaneous adsorption of contaminants onto GAC and their electrochemical oxidation. The results show that the main driver for the removal of organic matter is the adsorption onto GAC. However, when a current of 15 A m -2 is applied, electrochemical regeneration of the bed is achieved, 88% of the Chemical Oxygen Demand (COD) and 85% of the Total Organic Carbon (TOC) adsorbed is degraded, extending the life-time of the GAC bed and oxidizing the pollutants originally present in the water. In addition, a synergetic effect of adsorption and electrochemical oxidation in the 3D system has been observed, which enhances the performance of these two processes operating individually.