ACLS65,
As a matter of fact, it seems that the French BEA is investigating that exact scenario: a major wastewater leak that would have first permeated the a/c structure, then its freezing would have allowed the a/c in-flight breakout.
Article is available in French here:
Vol AF447: une nouvelle piste sur les causes du crash? - Yahoo! Actualités
(Sorry, had it just translated into English, but it was deleted and I'm too lazy to do it again...)