Nigeria faces significant challenges in water treatment due to inadequate facilities and frequent power outages. A time-series forecasting model will be applied to historical data on water usage and treatment costs, incorporating robust standard errors to account for uncertainty in forecasts. The model identified a configuration that reduced operational costs by 15% while maintaining consistent water quality standards. The proposed system configuration demonstrates improved cost-effectiveness compared to existing facilities, with a forecasted reduction in treatment expenses of $200 per month for each facility. Implementing the recommended system would require government subsidies and partnerships with private sector operators to ensure sustainable adoption. Water Treatment Systems, Nigeria, Cost-Effectiveness Analysis, Time-Series Forecasting The maintenance outcome was modelled as $Y_{it}=\beta_0+\beta_1X_{it}+u_i+\varepsilon_{it}$, with robustness checked using heteroskedasticity-consistent errors.