INTEGRATED PERFORMANCE ASSESSMENT OF DRINKING WATER TREATMENT PLANT, GROUNDWATER QUALITY, AND WATER SUPPLY SERVICES IN ETHIOPIA: A CASE STUDY OF ADAMA CITY

Abstract

Urban water supply systems are crucial for public health and sustainable development, yet urbanization exerts increasing pressure on water resources, exacerbating challenges such as scarcity and quality degradation. In Adama City, outdated infrastructure and weak management have reduced the reliability and quality of water services. This study assessed the performance of Adama City’s water supply system, integrating analysis of water treatment processes, groundwater quality, consumer perception, and operational efficiency. The key objectives included evaluating the treatment plant’s pollutant removal efficiency, groundwater compliance with WHO standards, factors shaping user perception, and the utility's operational status using IBNET indicators. Data were collected from July 2022 to December 2023 using laboratory tests, surveys, questionnaires, interviews, and field observations. Sampling included 108 composite samples from the CDWTP, 23 groundwater samples from both wet and dry seasons, and 435 households selected through stratified sampling. Additionally, 21 IBNET indicators were analyzed from the Adama Water Supply and Sewerage Service Enterprise (AWSSSE). Analytical methods involved ion-specific techniques for physicochemical analysis, membrane filtration for bacteriological testing, and statistical tools including one-way ANOVA, Pearson correlation (p < 0.05), and chlorine decay modeling. Software tools such as WaterGEMs, Python-VARMAX, and AquaChem supported advanced analysis. Groundwater quality was primarily categorized as Na-Ca-HCO₃ (36.36%) and Ca-Na-HCO₃ (27.27%), with fluoride, manganese, and iron within safe limits. However, free residual chlorine in the distribution system was below the WHO minimum of 0.2 mg/L, requiring attention. The treatment plant achieved a capacity utilization factor of 89% and contaminant removal efficiency of 68.28%. Microbiological quality met WHO standards for E. coli and coliforms, except for elevated total coliforms, indicating a need for improved disinfection. Only 41% of respondents expressed a positive perception of the service, citing issues such as water interruptions, billing errors, inconsistent supply, service failures, and delayed response. Despite this, 92% of households showed willingness to contribute to service improvements, with income, marital status, and home ownership influencing this willingness. The overall performance index averaged 51% (Efficiency Weighting) and 52% (Analytical Hierarchy Process), with moderate efficiency observed in infrastructure (81%) and water safety plan implementation (86%). The study highlights the need for infrastructure upgrades, improved user engagement, and better chlorine residual management to meet Adama City’s growing water demand. These findings provide essential insights for utility managers, policymakers, and researchers aiming to enhance the sustainability and resilience of urban water supply systems in rapidly urbanizing areas.