DETECTAR has supplied and installed 6 on-line chlorine meters. This equipment allows remote control of the levels of free chlorine in the water that circulates through the supply networks, a fundamental value to guarantee the correct quality of the water, and in this way avoid possible proliferation of bacteria such as Legionella. In this case, equipment has been installed that does not require water consumption, which allows for a simple and more efficient installation. The data are recorded by a Datalogger and transmitted daily to a web server from where they can be consulted.