How long can you survive without a pulse?
Your brain can survive for 3 minutes withouth a pulse, after that the chances of brain damage increase significantly. In the case of hyppthermia your brain lasts much longer.
Water is important to humans because without it we'll die. The human body is around 70% water. Humans are able to survive without water for a little while, but not as long as we can survive without food. We can survive without food for a week to a month and we can survive without water for three days to a week. Can you see the 'obvious' difference?