I would suggest that you look into UV light water purification.
Especially Camelbak Unit.
http://www.camelbak.com/PURIFICATION
It's rechargable via usb, and takes 1 minute to purify your bottle.
Of course you'd have to go and try one in store before buying, because it's another battery and all so it can be too heavy for your needs, but since you are bringing a solar panel anyway, maybe check it out!