Water intake, pleasure and water temperature in humans.

The influence of water temperature on intake and affective ratings was explored in human subjects. Dehydration whether by profuse sweating (body weight loss: 289 +/- 11 g, N = 20) or mountain climbing (body weight loss: 1660 +/- 58 g, N = 20) resulted in the same intake. Maximal intake was observed for water at 15 degrees C with respectively 199.0 +/- 17.0 ml and 222.7 +/- 17.4 ml. Colder and warmer water was ingested to a lesser extent. When 20 subjects were allowed to mix water to their preferred temperature, they chose 14.9 +/- 1 degree C and drunk 211.0 +/- 19.5 ml. Votes on a pleasure/displeasure scale increased from 50 degrees C to 0 degree C. Cold water was therefore both more pleasureable and less drunk. Dehydration resulted in a negative alliesthesia for warm water. Positive alliesthesia for cold water was probably the result of hyperthermia rather than dehydration.