People, it is darned foolish to load up on lots of water before you start up the trail!!! There is water at regular points along the trail.
I realize most don't care to do what I do, but this works for some: I dip and drink at just about every stream we come to along the way. If you don't feel comfortable doing that, take a break every hour or so and stop and filter (and drink as much as you possibly can (almost a pint) each filter stop. Then carry no more than a pint more, so it will get you to the next water stop. Only at Trail Camp should you fill up 3 liters. You can drink one on the way up, stash(hide) one at Trail Crest, and only carry the full one toward the summit.
TB40: No wonder you had such a hard day hike. 6L of water is 12 pounds!! Doing that nearly guarantees you won't complete the trip!
For more info on the water sources, go to this:
Links to important Whitney information, and look at the "Reliable Water..." links. The "Links..." post is the first thread in the "Reference" forum.
Regarding the "dip and drink" idea, I do that every where but the Trail Camp pond. There, I walk over to the inlet stream. I came back from a day hike last Sunday where 3 of us all did the same, and nobody had suffered any hint of trouble from doing that. My buddy even dipped handfuls of water from that spring on the switchbacks (I would have used only the top one, but he dipped from a few switchbacks below.) Bottom line is that the water is pure enough for anyone up there.
