Sensors and IoT for Water Quality Monitoring: A Systematic Review of Technologies and Field Validation

Water quality and availability require continuous, timely, and cost-effective monitoring solutions. This article presents a systematic review of literature published between 2020 and 2025 on sensors and the Internet of Things (IoT) for intelligent water monitoring, focusing on measurement parameters, communication architectures, and analytical approaches. The research contribution is the development of a structured taxonomy of sensors and analytes, a comparative analysis of network technologies and management platforms, and a synthesis of real-world applications across diverse domains with field validation. The methodology followed predefined inclusion and exclusion criteria, systematic variable extraction, and the PRISMA flow diagram, ensuring traceability and reproducibility, while validation indicators such as accuracy, drift, packet loss, and autonomy were normalized for comparison. The results highlight a convergence toward a physicochemical core of parameters (pH, temperature, turbidity, conductivity/total dissolved solids, and oxidation– reduction potential) and the predominance of LoRa/LoRaWAN integrated with platforms such as The Things Network (TTN) and ThingSpeak, combined with protocols including Message Queuing Telemetry Transport (MQTT), Node-RED, and Blynk. Applications include photovoltaic buoys for marine environments, rural networks with limited infrastructure, and UAV–LoRa relays extending coverage up to 10 km. Advances in wastewater treatment incorporate soft sensors and optical techniques, while analytics such as edge computing, machine learning, and federated learning demonstrate improved accuracy and timeliness of decisions. This review concludes with design and standardization guidelines addressing sensor– network–energy–validation integration and outlines future research on scalability, robustness, cybersecurity, and interoperability. The findings provide practical guidance for sustainable water management.