• • The zoned priority evaluation model, integrating structural defect density, cross-connection density, and pollution load, enables identification of high-risk zones, achieving a 27.64% reduction in dry-season external water inflow and raising terminal COD to above 230 mg/L.
• • Full-chain governance, including over 42 km of structural renewal and rehabilitation and 3,552 cross-connection rectifications, improved sewage collection rate to 76%, demonstrating system-level efficacy.
• • The smart O&M platform, with digital twin and closed-loop mechanisms, supports sustained performance by integrating monitoring, assessment, and rectification data, crucial for long-term operational stability.
• • The framework's effectiveness in a rainy southern city validates its scalability, offering a replicable model for similar urban areas facing infiltration and inflow challenges.