Hi,
Along my adventure, hikking, bicycle trips and alpinist mountain activities I used a lot of options, but two years ago, One friend mine who mades travels around the world shows me Steripen.
Steripen is a UV gatget that sterilize germs and viruses and they can not reproduce within our organism.
It comes with a adapter to use with Nalgene bottle.
Note: It only works well if the water is clean, to allow UV light arrives at the totallity of ammount of water.
