Water treatment facilities in Nigerian systems are crucial for ensuring safe drinking water and sanitation practices. However, their cost-effectiveness varies significantly across different regions, necessitating a methodological evaluation to optimise resource allocation. A panel data approach will be employed to analyse facility costs, operational efficiency, and user satisfaction across different regions. Econometric models will account for time-invariant and time-varying variables. Panel data analysis reveals significant cost differences (p<0.05) between northern and southern regions, with higher treatment costs in the north attributed to infrastructure challenges and varying water quality. The findings highlight the need for targeted interventions in high-cost regions, suggesting a shift towards more resilient and efficient facilities. Investment strategies should prioritise cost-effective solutions in northern regions, including pilot projects and technology upgrades that can be scaled up based on effectiveness. The maintenance outcome was modelled as $Y_{it}=\beta_0+\beta_1X_{it}+u_i+\varepsilon_{it}$, with robustness checked using heteroskedasticity-consistent errors.