This is a water quality monitoring device. It can be used to repair the damage caused by water pollution or for prevention. The solutions available on the Hungarian market are difficult to disassemble, which usually means that once they stop working, they cannot be reused. Their maintenance, transportation, and storing are problematic as well. In her project, the designer attempts to eliminate these problems. The structure of the buoy makes it easy to assemble and disassemble on a lake or a river and the contrasting colours improve its visibility. A user-friendly mobile app makes it possible to control several buoys at once, as it shows their location and lets the user know whenever some maintenance intervention is necessary. The project was created in cooperation with a producer of similar tools.