Last Tuesday, a French couple attempted a day hike in White Sands National Monument, and paid with their lives. Their son, age nine, survived. The family started the hike in the middle of a hot summer day with 40 ounces (1.2 liters) of water. Once the family became thirsty, the parents gave their son half the water they had. That act that most likely saved their son's life, but it meant that each adult had 10 ounces (0.3 liter) of water to drink on a blazing summer afternoon. That's less fluid than fits in a standard soda pop can.
For a day hike in the desert, however short, my minimum water supply is 2 liters (68 fluid ounces), almost seven times as much as each parent had. And most of my hikes
involve much cooler temperatures than you'll encounter at White Sands in the summer. In that type of heat, I've carried up to a gallon (3.8 liters) of water for daytime consumption,
and drank it all. Please learn from the tragedy that just took place, and never try to save weight by skimping on water.