Water Quality Assessment of Surface Water, Groundwater, and Wastewater in Bangui, Central African Republic: Physicochemical Parameters, Trace Metal Distribution and Microbial Contamination

Rapid urbanization and inadequate sanitation infrastructure threaten water security in many sub-Saharan African cities. This study presents the first integrated assessment of groundwater, surface water, and wastewater quality in Bangui, Central African Repub-lic, using physicochemical, trace metal, and microbiological indicators. A total of 28 sampling sites were analyzed using standardized methods, including ion chromatog-raphy, ICP-OES, ICP-MS, and membrane filtration. Results revealed a clear contamina-tion gradient. Wastewater showed the highest electrical conductivity, turbidity, chlo-ride concentrations, and microbial loads, reaching 2.41 × 10⁶ CFU/100 mL for total coli-forms and 1.93 × 10⁶ CFU/100 mL for fecal coliforms. Groundwater exhibited high ni-trite levels and low dissolved oxygen, indicating vulnerability to sewage infiltration. Surface waters were characterized by high turbidity and widespread fecal contamina-tion despite relatively good oxygenation. In contrast, trace metal concentrations gener-ally remained below World Health Organization guideline values. Geochemical anal-yses identified distinct elemental signatures for each water type. Microbial contamina-tion emerged as the dominant factor affecting water quality. High fecal coliform/fecal streptococci ratios (13.08-22.16) indicated predominantly human-derived pollution linked to untreated wastewater and inadequate sanitation systems. The association between elevated nitrite concentrations and fecal indicators suggests active contami-nation pathways connecting wastewater, surface water, and shallow aquifers. These findings highlight the urgent need for improved wastewater management, groundwa-ter protection, and long-term monitoring to ensure sustainable urban water security in Bangui.