The Watchtower's doctrine of the "waters above the earth" can be found, as has been mentioned, in the book FROM PARADISE LOST TO PARADISE REGAINED (1958), and before that in the book CREATION (1927), and before that in the book THE WAY TO PARADISE (1924). It is also present in AID TO BIBLE UNDERSTANDING (1971).
It is important to realize that this is not a new idea that the "inspired" writers of The Watchtower received from a whispering angel. It is an old, old, old doctrine that probably goes back to early Judaism if not even earlier than that. (I will invoke the intellectual powers of our mighty LEOLAIA for substantiation or falsification of my statement.)
For an organization that keeps shouting "Babylon the Great has fallen!" the Watchtower certainly relies on a lot of Babylonish Protestant and even non-Christian "pagan" teachings.
They depend upon an ignorant and uninformed customer base to buy the crap they're selling. The truth will set you free.