Minecraft wiki entry for Hopper, associated text: The accessible design should be used when the player, not redstone contraptions, will be using the stored items. When the bottom chest is emptied, only items stored in the adjacent hopper can fill it back up. Since the bottom chest is the only one which can be removed from with a hopper, it is impractical to use this for automation. Silos like this are commonly used in combination with sorting systems.