I think this is not implemented because it does not add much to game play other then a gimmick.
If you add finite water then you have to deal with how users will get more water, rain is cool but wouldn't add much when considering how much the steam engines would consume. You would make condensers ...

After reading this and considering it I think there are some rather simple fixes here and highlights why bots are better.

Belts cant move bots can.
Bots are instant when transferring goods to and from a container, and only have to consider travel times which can be researched to be increased ...