I usually carry a 1L bottle that I can filter with using the steripen and then a 2L bladder. I have thrown in a second 2L bladder on a few scouting trips and early season hunts where water is scarce, or just a long way down hill. I would like to find a fabric ultralight water bag that could hold 6 or so liters for hanging up a camp for cooking and drinking throughout the night and the next morning to avoid the trips to the creek.
I have a 2L Source, a 4L Dromlite with hydration kit, and a 10 L Drom bag that I use. I'll probably roll with just the 4L and the 10L for camp water this year like I did last year. Although I prefer the source2L over the 2 MSR bladders I have. IT doesn't have any nasty taste problems like some of the MSRs. I also take a nalgene bottle with me. Serves a lot of purposes and I normally use it for measuring out how much water to put into my meals.