LAUSR

Abstract Underground water is the main and probably the only source of drinking and irrigation in New Valley Governorate (Egypt). To assess water suitability for such purposes, 30 well-water samples (80-1300m depth) were collected from three oases i.e., El-Kharga, Baris and El-Dakhla. The pH values of these waters ranged from 6.5 to 7.88. SO 4 2 − was the dominant anion in such waters while Ca2＋ was the dominant cation. Concentrations of both ions (SO 4 2 − and Ca 2 + ) exceeded the maximum allowable limits for drinking and irrigation purposes. Although sodium adsorption ration (SAR) values did not exceed “10” in all waters samples; however, Mg-hazards and low infiltration rate might threaten the suitability of water for irrigation in many locations. Concentrations of Zn, Mn, Cu, Pb, Cd, As and Se were below the maximum allowable concentrations suggested by FAO for irrigation water. On the other hand, Fe was the only potentially toxic element (PTE) whose concentrations exceeded the permissible levels of WHO regulations for drinking water. According to the principal component analysis (PCA), these metals were originated from natural (Fe, Mn, Zn and Cu) and anthropogenic (As, Pb, Cd and Se) sources. Their existence represents potential chronic threats to children, particularly Fe, Mn, Pb and As. Moreover, the majority of water samples were within the moderate grade of irrigation quality index while exhibited low grades for the drinking quality index. Accordingly, more attention should be paid towards improving the quality of underground water in New Valley governorate for either drinking or irrigation purposes.