With ever increasing demand for clean water and healthy environment, the role of online analyzers has become more important in recent year. Conventional send-it-to-the-lab approach with periodic manual sample collection followed by laboratory analysis does not meet the monitoring requirements for the 21st century. Online analyzers can perform required analyses in a timely fashion, capturing critical events that would possibly be missed under a manual grab sampling regime. Online water analyzers have become integral tools in surface water and effluent monitoring in Korea. In 2005, Korean Ministry of Environment enacted a legislation on mandatory installation of online chemical analyzers at the end of pipe in large and medium-sized wastewater treatment plants. At present, real-time water quality telemonitoring systems (TMS) have been installed at 1,024 wastewater treatment plants in Korea. Recently, TOC analyzers are newly added to monitoring parameters. The amended law will be implemented from late 2021 to 2023, and new TOC analyzer market is expected to expand significantly. IoT based water monitoring technologies that measures water quality in real-time have made a significant progress for source water surveillance and environmental protection. Korea Environment Co., K-Water Co., and Korea Rural Co. are expanding real-time water monitoring stations in rivers, streams and reservoirs. More than 300 stations are expected to be installed from 2020 to 2023.