Disinfecting water is an important process and a challenge in the fight against disease, and this applies not only to drinking water suitable for human consumption, but also to water used for non-potable purposes. This book aims to develop a closed-loop automated dosing system for disinfecting rainwater for non-potable consumption using sodium hypochlorite as a disinfectant. The prototype was developed using a microcontroller, a peristaltic pump, a 5-volt relay, a display and a sodium hypochlorite level sensor and a rainwater sensor, the latter of which is used to check the discrete volume of this fluid. During the calibration tests, the prototype performed very well, with synchronisation between all the devices involved. From reading this book, it is clear that it is feasible to provide a disinfection treatment for rainwater for non-potable purposes, accessible to any public, using sodium hypochlorite in an automated, low-cost way, eradicating the pathogens present in this type of water.