Years ago, I was camped out in the desert at a natural spring. There is another spring about 2.5 miles up the valley that I wanted to check out. I set out with eight (8!) water bottles. I got about two miles - the oasis around the next spring was visible in the distance. I had already emptied four water bottles, was starting to show the first signs of heat stroke, and didn't know if there was potable water at the next spring. I was forced to turn around and coast down the gentle grade back to camp. I used up another three bottles on the return!
Back at camp with other people around, I sat in the shade and chugged several more bottles of water.
The temperature that day: It had "cooled down" to 105 from 113 the day before.