I agree with the idea of taking a filter, not bottles. If you are a minimalist and want to keep things simple for a single day's hike, you can also add 4 drops of household bleach to a liter of water and let it sit in your bottle for 30 minutes. You wll be safe from just about everything except cryptosporidium...which is not common in the High Sierra.
But let's take your hike for example. First of all, drink a lot of water BEFORE you start your day-hike. One liter per person. If you do this right, you'll have to stop and pee at some point in the first hour. That's fine. It means you are hydrated. And now you have to hike about six miles to Glen Aulin. If you hike at 2 miles per hour (which is a bit slow) that will take you three hours--if you don't stop and rest every ten minutes because your feet hurt, back is bothering you, shoes need to be retied, somebody has to pee, want to take a picture, need a snack, etc..
Ask each hiker to carry one liter of water for their personal use. That should be enough to get you most of the way to Glen Aulin.
Along the way, you will see the Tuolumne River and various creeks--those are sources of water. There is obviously water at Glen Aulin---the Tuolumne River runs through it. So throughout this hike you can pump or treat water and replenish your body/bottles. if you are using the bleach, always have one bottle full and ready to drink, while at least one other one is going through the 30 minute treatment process.
Take a break at Glen Aulin, eat lunch and do all the things that I listed above. But first, finish all the water you carried, and treat/pump to fill them again. Stay at least 30 minutes, so you can drink MORE water before you leave Glen Aulin. Pump and or treat your bottles again, just before you leave Glen Aulin.
Now you have one liter person to carry back to the trailhead, and should be fully hydrated. If you finish that water, pump/treat another bottle so that within 30 minutes you have more to drink. If you stop once along the trail to do this, you'll have consumed five liters of water on the trail....and can get as much as you want to drink at the trailhead/Tuolumne Meadows.
And try to remember that you never get any points for arriving at any destination with water in your bottles. Water is to drink. Do it on the trail where it will do you some good.
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Or just read a good mystery novel set in the Sierra; https://www.amazon.com/Danger-Falling-Rocks-Paul-Wagner/dp/0984884963Edited 1 time(s). Last edit at 08/02/2011 08:36AM by balzaccom.