Following Bob Rockwell's example,
I have always drunk the water in the Whitney Zone unfiltered. I was up there last spring, drank from the North Fork, and various places along Lone Pine creek. We camped 3 nights at Trail Camp. The pond still had several feet of snow cover, and the only water available was snow melt running across granite slabs just below the pond. I repeatedly refilled my water supplies from that spot, and never experienced any trouble during or after the trip. When the pond is melted out, I prefer to go to the stream flowing into the pond and fill up at that point. By now, the water may be flowing across the switchbacks above Trail Camp, about switchback #25. I would drink that water any time, as well.
Of course your preferences matter the most, so it is up to you what you do.