Thanks guys. Hope it works out as well for you as it does me!
I would be careful what kind you buy. I'm not sure how durable they are, and have read some bad reviews of the cheaper ones. I bought mine at REI as they always stock the best shit and have a no questions return policy, not to mention awesome customer service ... and 10% back yearly for members.
If you have problems with one breaking, post it here for others.
I've never had one of those before. Let's say you are having to fill and tote it multiple times from a lake or stream. Is it easy to fill up fully by dipping it under the water or is it meant to be filled from a hose or spicket?
Well, it's much easier from a spigot, but could certainly submerge it to fill it. If it's in a backpack, however, you'd have to either take it out of the pack or submerge the entire pack.
What I would probably do is stash a pitcher near where you regularly fill up, and use the pitcher to fill the pack a few quarts at a time.