If you intend to travel where there are unreliable water sources then you need a water filter or purifier. Filters and purifiers protect against lots of parasites and water borne diseases, particularly Gardia. A ceramic filter will remove anything (bugs & dirt) in the water down to 0.2 microns while a purifier kills the bugs in the water but removes nothing. MSR filters screw onto the Nalgene bottle range to make for trouble free filtration.
Prevent silt getting into your main filter with this handy add on, 26g.