Groundwater resources across Europe and Africa face escalating pressures from global climate change, intensive agricultural practices, population growth, and emerging chemical pollution. To enhance water security and protect subterranean aquifers from overexploitation and degradation, Managed Aquifer Recharge (MAR) has emerged as a vital climate-adaptation strategy. By intentionally directing alternative water streams—such as surface water, reclaimed municipal wastewater, and agricultural irrigation water—into subsurface geological formations, MAR schemes restore depleted groundwater levels, halt coastal seawater intrusion, and establish strategic freshwater reserves. However, the long-term success and public safety of MAR depend fundamentally on the quality of the recharge water and the operational reliability of advanced treatment technologies capable of mitigating aquifer well clogging, diffuse nutrient leaching, and contamination by persistent micropollutants.