The notion that camels can go without water completely is a myth, nor do they use their extraordinary humps as storage tanks for water.
The fact is, camels are able to make long, burdened treks across blazing deserts where oases are few and far between because of their uncommonly economical use of water.
They are able to tolerate a greater depletion of body water (30 percent) than human beings, who can stand to lose only about 12 percent, because camels lose water from their body tissues alone, leaving the water content of the blood fairly constant. Most mammals, on the other hand, lose water from the blood, which becomes increasingly viscous and sluggish until it no longer carries away a sufficient amount of metabolic body heat and leads to heat prostration, collapse, and possible death.
Camels can also consume up to 25 gallons of water in a very short time, taking in as much as they have lost and thoroughly diluting their body tissues without dying of water intoxication (a condition in which the cells are overly flooded) as would other mammals.
Camels can tolerate not only wide variations in water content, but also a rather broad range of body temperatures, which helps them use water economically.
During the summer in North Africa, for example, a camel’s temperature might be 93 degrees Fahrenheit in the morning and rise to 105.3 degrees Fahrenheit in the afternoon. The camel does not begin to sweat, however, until the higher temperature is reached, which means water loss by sweating is limited. The coarse hair on the camel’s back helps block some of the sun’s heat, but it is well ventilated enough to allow cooling by quick evaporation of sweat.
Little water is lost in the camel’s feces. The rate of urine flow is low, and, to compensate, the kidneys secrete a very low amount of urea, particularly when protein is scarce.
To help them survive in the torrid deserts of Central Asia, India, and North Africa, the camels’ metabolic rate is low, allowing these phlegmatic animals to live on low grade, dry food and to stay away from water holes for stretches of two weeks or more.