Once you pop the top off the soda bottles they look generic. The tops identify what is inside the bottle. Once the top comes off all of the bottles are simply fanta bottles with different coloured liquids.
You can tell the difference between soda water and tonic water by the smell (but who wants a bartender's nose in their drink) and also if you shake the bottle - soda water barely fizzes, tonic water comes flying out and gets everywhere.
Yep, used to be a bartender in Belize.