I used two Platypus bladders for my drinking water treatment/storage needs. Yes, I carried two bladders and two hoses the entire length of the trail. No, I didn't need to carry two bladders and two hoses the entire way, one of each would have been fine; neither of the bladders or hoses ever leaked or gave me the slightest trouble.
I tried many times to put one in a hiker box, but I couldn't do it - the long-ingrained instincts from my time in the submarine navy, in this case the desirability of having a back-up in case something fails, were too strong to overcome. So I carried two...they weren't really that heavy...at least, I can say that now.
The good thing about the bladder/hose setup was that I didn't have to stop to get a drink. The bad thing was, in order to refill the bladder, I had to pretty much pull everything out of my pack to get the bladder out. Some newer packs can hold the bladder outside the pack, just behind the suspension system. Anyway, the limitations of my situation sort of led me to carry more water than I might have otherwise, if it had been more convenient to fill up more often. I started each day with about 1.5 liters or so, and refilled usually just once, usually somewhere near the middle of the day.
I didn't carry a filter. If I thought the water needed treating, I used chlorine or iodine tablets. If the source was a spring, I didn't treat the water; I didn't treat any water at all for the first month, the springs in Georgia, North Carolina, and Tennessee were everywhere! And, because it was so rainy this summer, there were springs in lots of places, only parts of New York and Connecticut were problematic for water this year.
I think next time I hike, instead of the tablets, I'll take a small bottle of bleach with a dropper to treat water. That seemed a lot easier than filtering or using the two-part Aquamira drops.
One last point: you can't refill a bladder by submerging it, you need a cup or something to fill it with. It probably seems obvious, and it should be...I still had to prove it to myself by trying it...luckily, I was by myself - only the frogs saw me looking silly!