Contrast the mixing of spirits into strange, blue concoctions that led to sour affairs with heartless women and dead-ended pecuniary aspirations, with the pure clear water at the waterfall that encapsulated the moment he embraced true love.
I think they were a metaphor for dreams. The main character in this film was dreaming of a better life which he thought meant money, fancy things, penthouses. The exotic cocktails he mixed were showy and colorful like the things he desired. In Jamaica he briefly finds true love drinking simple Red Stripe beer, but goes back to mixing fancy drinks to impress a rich city lady. In the end, all of his dreams are fulfilled when he goes back to pulling drafts in a neighborhood bar.