Water treatment facilities in Tanzania face challenges related to cost-effectiveness, necessitating a methodological approach that can evaluate their efficiency. A quasi-experimental design will be employed, including pre- and post-treatment data collection to measure the impact on cost-efficiency. Statistical analysis will use regression models with robust standard errors to account for potential confounders. The preliminary findings suggest a significant reduction in operational costs by 15% after implementing the recommended treatment protocols. The quasi-experimental design provides valuable insights into cost-effectiveness, which can inform future investments and policy decisions in water infrastructure. Policy makers should consider the results of this study to allocate resources more efficiently for water treatment facilities in Tanzania. quasi-experimental design, cost-effectiveness, water treatment, Tanzania The maintenance outcome was modelled as $Y_{it}=\beta_0+\beta_1X_{it}+u_i+\varepsilon_{it}$, with robustness checked using heteroskedasticity-consistent errors.