Spatiotemporal Assessment of Physicochemical Water Quality in the Al-Aziziyah–Al-Hafariya Water Treatment System, Wasit, Iraq
Abstract
This study aimed to evaluate the physicochemical characteristics of water within the Al-Aziziyah–Al-Hafariya unified water treatment and distribution system in Wasit Governorate, Iraq. Water samples were collected monthly from six locations representing the raw water source, treatment stages, and the distribution network from September 2025 to February 2026. Key parameters were analyzed, including temperature, turbidity, total suspended solids (TSS), total dissolved solids (TDS), electrical conductivity (EC), salinity, pH, dissolved oxygen (DO), biological oxygen demand (BOD), alkalinity, hardness, residual chlorine, sulfate, nitrate, and phosphate. The results showed significant temporal variations (P ≤ 0.05) in most parameters, while spatial variations were generally insignificant across all sampling sites. Temperature, TDS, EC, salinity, and hardness were higher during autumn and decreased in winter. In contrast, dissolved oxygen and nutrient concentrations increased during colder months. Turbidity and TSS exhibited seasonal fluctuations. Critically, residual chlorine fell to zero at all six sampling sites during January and February, well below the WHO minimum recommendation of ≥0.2 mg/L at the point of delivery, representing a serious public health concern regarding microbiological safety. Statistically significant spatial variation (P ≤ 0.05) was observed in phosphate concentrations, with elevated levels at distribution-network endpoints (S4–S6, mean 0.238–0.257 mg/L) compared to raw and treated water sites (S1–S2, mean 0.174–0.177 mg/L), suggesting localized contamination within the distribution network. In conclusion, seasonal factors play a dominant role in influencing water quality, while the treatment and distribution system ensures relatively uniform water characteristics across the study area. These findings emphasize the importance of continuous monitoring and optimization of treatment and disinfection processes to ensure safe drinking water quality.