Brief Answer: Need more info Detailed Answer: Hello Thanks for the query A human being cannot survive extreme dehydration for more than 24-36 hours. The thirst center in the brain get activated when there is loss of fluid either by sweating or working or loss through skin and automatically one tends to drink water and rehydrate. A minimum of 1 litre of water is required by our body per day to keep the metabolism going. Signs and symptoms of dehydration are 1. Muscle cramps 2. Headache 3. Giddiness 4. Thirst 5. Lethargy 6. Extreme fatigue 7. Palpitation ( feeling of ones own heartbeat) 8. Loss of consciousness and altered behavior I hope I was of help. If you have more specific queries please get back to me Regards

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