Ye, less water could do, but only to Trail camp, and If I would put less water to my camel back, I would have to refill few times.
From Trail Camp to the summit there is no water at all, so I had to have all 3 liters, which was exactly what I've used, but I had only day bag so didn't really matter in that part of the hike. (little day pack from the top of my kelty)
