Water is the most critical item: There have been a few times in my life when I have gone three or four days without food, but only once did I go twenty-four hours without a drop of water (or any other fluid). From that experience, I can honestly say that I would rather be four days without a bite of food than a single 24-hour day without water.
   I want to apologize that information in some of these links is shared by other topics because I felt that it was quite relevant to both (“Heating Water” is repeated in greater detail under “Energy” for instance).