Water quality assessment and hydrochemical characterization of Zamzam groundwater, Saudi Arabia

This study focuses on chemical and microbial analyses of 50 Zamzam water samples, Saudi Arabia. The soluble ions, trace elements, total colony counts, total coliform group, and E. coli were determined and compared with WHO standards. The obtained results indicated that the dissolved salts, soluble cations and anions, Pb, Cd, As, Zn, Cu, Ni, Co, Fe, Mn, Cr, PO4 3−, NO2 −, Br−, F−, NH4 +, and Li+, were within permissible limits for all samples. Yet, 2% of waters contain NO3 − at slightly high concentration. The water quality index (WQI) reveals that 94% of the samples were excellent for drinking (class I). While the remaining was unsuitable due to total coliform group contamination “class (V)”. Durov diagram suggest no clear facies and dominant water type can be noted. It indicates mixing processes of two or more different facies might be occurring in the groundwater system. All studied waters were undersaturated with respect to halite, gypsum, fluorite, and anhydrite. These minerals tend to dissolve and increase water salinity. A direct relationship between Zamzam water salinity and rainfall is recorded. The water salinity fluctuated between 4500 mg L−1 (year 1950) and 500 mg L−1 (year 2015) based on rainfall extent. The approach applied can be used to similar groundwater worldwide.