As my long-winded and complicated response at
http://yosemitenews.info/forum/read.php?3,43276,43848#msg-43848
may be hard to read. Some may find the following to be more useful:
Simple graph of ranges of daily water intake needed for adults under different conditions
http://www.jacn.org/content/26/suppl_5/597S/F1.large.jpg
which is from the free review article available at: http://www.jacn.org/content/26/suppl_5/597S.long
Further and detailed additional free articles on topic are available here:
Institute of Medicine has a book available dealing with dietary water and sodium for free by pdf file (sign in required) at:
http://iom.edu/Reports/2004/Dietary-Reference-Intakes-Water-Potassium-Sodium-Chloride-and-Sulfate.aspx
And some info with a slight Gatorade bias is available at:
http://www.jacn.org/content/26/suppl_5/542S.full.pdf+html
The cure for a fallacious argument is a better argument, not the suppression of ideas.
-- Carl Sagan