AlanK wrote:I would simply not do this hike without having some experience on lesser outings in places that are hot and involve a lot of climbing. That experience gives on a basis for judging one's personal water needs. I'd then err on the side of more water. I would never base my water supply decision solely on what someone else carries.
Alan brings up a good point. How much water you need and how much water I need can be very different. I need more than most people. Some people don't bring enough, apparently preferring (or at least not minding) being dehydrated so they don't have to carry the weight.
That said, I often as others I'm hiking with how much they are carrying. This both lets me know who is not prepared if I think it's too low, or, if everyone has much more or less than me, tells me I need to rethink
for myself how much to carry.
For out and back hikes, I often drop 2-liters part way up and pick it up on the way down. It saves hauling 5 pounds to the summit when I don't need it until the return trip.