Sustainable groundwater use is becoming increasingly rare, as more regions cross critical thresholds of aquifer depletion. Groundwater decline has accelerated globally over recent decades, driven primarily by over-extraction, especially for agricultural irrigationAgricultural irrigation, which now relies on groundwater for over 40% of its supply. Projections suggest that by 2050, annual groundwater withdrawals will reach 1,535 km \(^{3}\) , and urban areas where groundwater is often the primary source of freshwater are placing growing demands on already stressed aquifers. Rapid urbanization in typically arid regions is intensifying groundwater dependence, exacerbating risks to reliable water supply for drinking, domestic, and industrial uses. This increasing reliance on groundwater has far-reaching implications. When extracted, groundwater transitions from long-term sub-surface storage into the active hydrological cycle, contributing to streamflow, evapotranspiration, and eventually atmospheric or surface losses. This redistribution effectively depletes global groundwater stocks. As discussed in this chapter, the combination of population growth, expanding agricultural irrigation, and rising urbanization is reshaping global groundwater dynamics. These trends underscore the urgent need for sustainable management strategies to preserve groundwater as a critical buffer against climate-induced water shortages and to ensure the long-term resilience of both rural and urban water systems. This chapter discusses some case studies on groundwater use in Europe, Middle East, Australia, Africa, North America, Asia, and South America, offering an inventory of global groundwater extraction across continents. It also examines the impacts of urbanization on groundwater levels and flow, as well as the ecological consequences associated with excessive groundwater withdrawal.