Well, that sounds like you carried 4 liters from Outpost. Most people talk about taking at least 3 from Trail Camp, so you had probably already consumed more than 1 by the time you got to Trail Camp. Bob R takes 2, and keeps refilling with snow on the way up, caching a full one at Trail Crest for the way down. But that requires warm enough temps so that the snow will melt.
As for the metallic taste: Try filtering some tap water at home with your filter and canteens. Then slosh it around every so often for a few hours. It might be the filter or the containers.
Also: I discovered Nuun electrolyte tablets this summer. Those, mixed with some kool aid mix makes the water taste like a carbonated soft drink. I really like it. Tablet alone helps a lot, too.
Just so you know, some of us old-timers just dip and sip, all the way. I avoid the Trail Camp pond, and walk the few yards off trail to the inlet stream, where I drink copiously and fill containers.
Here's from the first topic in the Reference forum:
Water discussions (Drink untreated, or filter/treat/boil/etc.)
Water and Giardia around Mt. Whitney 60,000 Liters of Water Consumed -- Untreated Filter question (links to studies, etc.)
