Internet of things-based water quality monitoring: A case study in the coastal areas of Semarang city and Kendal Regency, Central Java, Indonesia

Coastal areas serve as vital habitats for aquatic organisms, but they are facing increasing environmental degradation due to pollution and human activities. Continuous and accurate water quality monitoring in these regions is essential for sustainable ecosystem management. This study presents a novel Internet of Things (IoT)-based water quality monitoring system that distinguishes itself from prior approaches through its real-time, second-by-second data acquisition, on-site display, and low-cost architecture tailored for tropical coastal environments. The system utilizes a Node MicroController unit microcontroller integrated with pH, temperature, and total dissolved solids sensors. It displays data through a liquid crystal display and transmits it to a cloud-based server for further analysis. Calibration of the sensors resulted in an average error rate of 2.0%, which is within the acceptable range for practical water quality assessment. A key innovation of this system is its continuous monitoring and instant detection of deviations in water quality parameters, enhancing the responsiveness to potential environmental threats. This solution reduces the dependence on labor-intensive manual sampling and enables long-term historical data storage and analysis, supporting data-driven decision-making by researchers and local authorities. The results demonstrate that the IoT-based monitoring system is reliable, cost-effective, and adaptable, making it a promising tool for the sustainable management of coastal water ecosystems in Semarang city and Kendal Regency, Central Java, Indonesia.