Microbiological Contamination and Physicochemical Characteristics of Drinking Water in Secondary Schools, Al-Hilla City, Iraq

Abstract

Ensuring safe drinking water in schools is essential for protecting adolescent health and achieving Sustainable Development Goal 6. Evidence from Iraqi secondary schools remains limited. This study aims to assess the physicochemical and microbiological quality of drinking water in Al-Hilla City. A cross-sectional study was conducted between September 2025 and February 2026 in 17 secondary schools in Al-Hilla City, Iraq. Drinking water samples were analyzed for physicochemical parameters (pH, turbidity, total dissolved solids, hardness, calcium, magnesium, nitrate, chloride) and microbiological indicators (total coliforms and Escherichia coli) using American Public Health Association standard methods. The results were compared with World Health Organization and Iraqi drinking water standards. The results of the study reveal that bacteriological contamination was detected in 35.3% of samples, indicating non-compliance with World Health Organization guidelines. Most physicochemical parameters were within permissible limits; however, total dissolved solids exceeded standards in 70.6% of samples, turbidity in 11.8%, and total hardness in 23.5% of water samples, and calcium exceeded the Iraqi standard in 17.6% of water samples. Although chemical safety was generally acceptable, the presence of microbial contamination and elevated dissolved solids in several schools suggests potential health risks. Routine monitoring, improved disinfection, and maintenance of school water systems are recommended to ensure sustained compliance with drinking water standards.