Effective strategies for designing and managing coastal defenses against erosion require a multidisciplinary approach. From a regulatory perspective, the Italian Dm 152/2022 “End of Waste” governs the reuse of construction and demolition waste (C&D waste) and other inert mineral waste. A noteworthy aspect of this Dm is that it allows such waste to be used for the morphological restoration of eroded coastlines, through beach replenishment and the reestablishment of coastal dunes. This circumstance serves as an opportunity to incorporate porous materials with predetermined granulometric characteristics and values of the main hydraulic parameters, such as hydraulic conductivity. In an attempt to improve the current understanding and shed light on the potentialities of this approach, we utilized the Hydrus-2D software. We investigated whether the implementation of local heterogeneities made by recovered materials with specific grain sizes could effectively regulate the interaction between the sea and groundwater. This could control infiltration, exfiltration, and velocity distribution in a coastal dune, thereby mitigating erosive phenomena. A comparison is made between different scenarios in which heterogeneities have been created inside a dune using highly and lowly conductive materials. We consider cases where the groundwater level is higher than the sea level and vice versa. Results indicate that soil heterogeneity can be used to optimize infiltration adn exfiltration processes. Materials with lower hydraulic conductivity values generally limit velocity fields and exfiltration processes from the dune surface. This could limit erosion, especially in cases where groundwater level is higher than sea water level.