Comprehensive Evaluation of Drinking Water Quality and the Effect of the Distribution Network in Madinah City, Saudi Arabia

Access to safe drinking water is a critical public health priority, particularly in arid regions such as Saudi Arabia where water scarcity and reliance on desalination present unique challenges. This study was conducted to evaluate the quality of drinking water in Madinah City and to examine the potential influence of the distribution system on water quality before it reaches consumers. Water samples were systematically collected from both primary and secondary reservoirs as well as from points within the distribution network. The samples were analyzed for key physical parameters, inorganic constituents, heavy metals, volatile organic compounds, and microbiological indicators using standard laboratory procedures. The results demonstrate that Madinah’s drinking water meets national and WHO drinking water quality standards, with most parameters well below the maximum contaminant levels (MCLs). Slight variations were observed between the primary and secondary reservoirs, likely due to the blending of desalinated seawater with groundwater. Importantly, six heavy metals—iron (115 µg/L), aluminum (48.5 µg/L), copper (58 µg/L), lead (0.22 µg/L), magnesium (7.15 µg/L), and strontium—were detected at higher concentrations in the distribution system compared to the reservoir sources (15, 15, 8.5, <0.05, and 0.71 µg/L, respectively). Although these values remained within acceptable limits, their presence suggests potential leaching from distribution pipes and underscores the need for continuous monitoring. This study provides an evidence-based assessment of water quality in Madinah, offering valuable insights for water authorities to strengthen monitoring programs and ensure long-term protection of public health.