Real-Time detection of sewer water levels and blockages using UHF-RFID sensors

Sewer blockages and inflow-and-infiltration (I/I) pose significant challenges to aging urban infrastructure, often leading to sewage overflows and environmental contamination with human pathogens. Conventional detection methods, including ultrasonic sensors, CCTV, infra-red cameras, and fiber-optic distributed temperature sensing systems, are costly, labor-intensive, and limited in scalability. This study introduces the use of ultra-high frequency radio frequency identification (UHF-RFID)-based sensors for real-time monitoring of water levels and surface flow velocities in simulated sewer systems, offering a novel, robust, and cost-effective solution for detecting sewer blockages and I/I events. To achieve this, we developed a UHF-RFID water depth ruler that demonstrated a near-identical accuracy to conventional point gauges (R² > 0.998) in various flow conditions. Additionally, our custom-designed UHF-RFID-based floating sensors accurately quantify a wide range of surface velocities under turbulent conditions (up to 72 L/s) in a controlled flume environment. By correlating surface flow velocity and water depth profiles, we could accurately identify blockage severity and detect point source I/I events in real-time within an open channel flume. The findings highlight UHF-RFID sensors as a low-cost, robust, and high-throughput tool for continuous sewer monitoring. Their scalability and ease of deployment make them ideal for integration into complex smart sewer infrastructure, significantly enhancing buried asset management. This research presents an innovative advancement in sewer monitoring technology, offering municipalities a scalable and efficient approach to maintaining the health and functionality of urban sewer networks while mitigating the risks of overflows and environmental pollution. © 2025 The Authors. Published by Elsevier Ltd.