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To avoid death by dehydration, a person crossing the desert should drink a minimum of 3 gallons of water per 24 hour period during the cooler months, November through April. And 5 gallons during the hotter months, May through October. A gallon of water weighs approximately 4.5 lbs.

There are very few natural water supplies in the Southwest and by the hotter months they've dried up or become brackish.

Some water sources have been intentionally contaminated or poisoned since September 11, 2001.