How long can a human survive without water?
Rule of threes (survival)
You can survive three minutes of severe bleeding, without breathable air (unconsciousness generally occurs), or in icy water. You can survive three hours in a harsh environment (extreme heat or cold). You can survive three days without drinkable water. You can survive three weeks without edible food.
Addax
The addax are amply suited to live in the deep desert under extreme conditions. They can survive without free water almost indefinitely, because they get moisture from their food and dew that condenses on plants. Scientists believe the addax has a special lining in its stomach that stores water in pouches to use in times of dehydration. They also produce highly concentrated urine to conserve water.[16] Pale colour of the coat reflects radiant heat, and the length and density of the coat helps in thermoregulation. In the day the addax huddle together in shaded areas, and in cool nights rest in sand hollows. These practices help in dissipation of body heat and saving water by cooling the body through evaporation.[3]