If you need to fill a bunch of water bottles, you could do so using your hands and a sink… or you could automate the task like YouTuber Easy HomeMade Projects.
The build is controlled by an Arduino, spinning a carousel of a half-dozen bottles under a fill hose with a stepper motor and timing belt. When in place, the system’s water pump is activated, filling each bottle for a set length of time.
For alignment, the device is rotated into a starting point sensed with a small switch, and the process is started with a small pushbutton. It then cycles through six positions, beeping to indicate when each is done.