i was at sportsmans warehouse with intentions of buying the right sized backpack when i thought of the water issue do i buy a backpack with a hydration unit, pack bottled water,or as the young man offered there is another solution-if you know there are streams or rivers you can use this plastic bottle with the filter and keep refilling i was not aware that even these pristine waterways contain all sorts of micro-organisms like crypto.and more commonly giardia has anyone gotten sick from drinking the water, what are your preferences and is anyone familar with this bottle and filter-its guaranteed to eliminate all these nasty bugs up to i think 2000 refills.thanks