Wikipedia says:
Dehydration symptoms generally become noticeable after 2% of one's normal water volume has been lost. Initially, one experiences thirst and discomfort, possibly along with loss of appetite and dry skin. Athletes may suffer a loss of performance of up to 50%, and experience flushing, low endurance, rapid heart rates, elevated body temperatures, and rapid onset of fatigue.
...
The symptoms become increasingly severe with greater water loss. One's heart and respiration rates begin to increase to compensate for decreased plasma volume and blood pressure, while body temperature may rise because of decreased sweating. Around 5% to 6% water loss, one may become groggy or sleepy, experience headaches or nausea, and may feel tingling in one's limbs (paresthesia). With 10% to 15% fluid loss, muscles may become spas.tic [it's a medical term!], skin may shrivel and wrinkle, vision may dim, urination will be greatly reduced and may become painful, and delirium may begin.
Losses greater than 15% are usually fatal.
http://en.wikipedia.org/wiki/Dehydration
21-Sep-2006, 16:28 
antonye
Threaded Mode