Not quite sure why the man in the film seems so fixated with the water content of the body and why, as man ages, the  water content goes down, thus, drying up.  Surely, the writer has a vital message in doing so, on giving emphasis on this idea.  From what is presented on the animated film, it seems that aging seems to be the focus here. On the other hand, the man acts and feels weird when Emily is mentioned, giving us the notion that he has strong emotions for this girl.  So, what could be the connection of aging,  body water content and emotions? I would like to presume that all is interconnected on this level.  Film scoring was laudable and while I cannot truly fathom what it is the writer intends to convey,  I would like to believe that she is stressing the importance of water vis a vis man's lifetime.