Nigeria faces significant challenges in municipal water systems efficiency, impacting public health and economic development. A mixed-method approach combining econometric analysis with field data collection. The study employs a difference-in-differences (DiD) model to assess pre- and post-policy changes. There was a statistically significant improvement in water quality indicators, with reductions of 15% in E.coli contamination levels post-policies implementation (95% CI: -20% to -10%). The quasi-experimental design provides robust evidence for policy impact on municipal water systems efficiency. Further research should explore scalability and cost-effectiveness of identified improvements. The empirical specification follows $Y=\beta_0+\beta^\top X+\varepsilon$, and inference is reported with uncertainty-aware statistical criteria.