This study investigates the spatiotemporal evolution of groundwater quality and hydrochemical characteristics in the Middle Eocene aquifer of West Mallawi, El Minya Governorate, Egypt, using comparative datasets from 2016 to 2024. As the region's principal source of domestic and agricultural water, the aquifer is increasingly stressed by overextraction, urban encroachment, and contamination. A total of 59 groundwater samples were analyzed for pH, electrical conductivity (EC), total dissolved solids (TDS), and major ions to evaluate temporal shifts in water quality. Results show a slight decline in water levels, from 98 m in 2016 to 97 m in 2024, and a shift toward more alkaline conditions, with pH increasing from 7.6 to 7.9. Salinity also rose, with EC increasing from 1692 to 1784 μS/cm and TDS increasing from 1083 to 1142 ppm. Critically, chloride concentrations more than doubled, exceeding WHO limits, while sulfate declined. Overall water quality deteriorated, with the Water Quality Index changing from predominantly “Excellent” in 2016 to mainly “Good” in 2024; several samples recorded WQI values greater than 100, indicating poor quality for consumption. Hydrochemical facies, illustrated by Langelier–Ludwig diagrams, remained dominated by the SO₄·Cl–Na type, while multivariate analyses (PCA and hierarchical clustering) confirmed evaporation, ion exchange, and intensifying anthropogenic inputs as the main drivers of groundwater salinization and contamination. Sentinel-2 imagery and NDVI-based land-use/land-cover analysis revealed rapid urban expansion into agricultural zones and a marked reduction in vegetative cover, reinforcing the connection between land-use change and groundwater degradation. These findings demonstrate accelerating aquifer deterioration and highlight the urgent need for stricter groundwater abstraction controls, contamination safeguards, and integrated land–water management to ensure long-term water security in West Mallawi and comparable arid settings.