<p>The vast Western Desert of Egypt may appear as an endless expanse of barren sand and rocky plateaus, but beneath this seemingly lifeless landscape lies one of the most significant water resources in North Africa i.e. the Nubian Sandstone Aquifer System (NSAS). Covering large portions of Egypt, Sudan, Chad, and Libya, the NSAS is a vast underground reservoir that plays a pivotal role in the water supply of Egypt's arid regions. The present study re-evaluates the hydro geochemical conditions of the Nubian Sandstone Aquifer, focusing on water quality and its suitability for various uses. Hydro chemical analysis of 350 groundwater wells across the region involved the assessment of physical and chemical properties, Results indicate that most samples EC, TDS, pH, and concentrations of major anions and cations generally conform to (WHO) standards for drinking water. The high content of iron in the groundwater samples of the NSAS may be attributed to the iron-oxide minerals (Hematite and Magnetite) which is rich in the rocks of the western desert. Therefore, water treatment is necessary to reduce iron concentrations to levels suitable for drinking. A hydro-geochemical evaluation was carried out depending on statistical analyses. Additionally, Piper, and Schoeller diagrams were also used. Factor analysis revealed key factors contributing to groundwater quality variance across different regions, accounting for 58.1% in Bahariya, 46.73% in Farafra, 75.6% in Dakhla, 38.6% in Kharga, and 45.6% in Siwa. This study found that over-exploitation of groundwater will cause deterioration of groundwater quality due to over-pumping and therefore, the Nubian sandstone aquifer should be withdrawn based on the safe yield calculation in the aquifer.</p>