Yes! For use in the backcountry, first, take out the Filter Straw and use PureVis™ Adventure Mode (double-click) on its own. Then, put the Filter Straw back in. Finally, fill with water that is clear to the eyes with no sediments.
As a rule of thumb in the backcountry or on hikes, stick to running water sources such as rivers, streams, or waterfalls, further away from vegetation.