Got some of these bottles
These are fantastic for trekking abroad for two reason:
1) They can be used as emergency water carriers for when your bottle breaks, and also if you miscalculated the amount of water you'll need and suddenly have to carry more water
2) Before and after trekking, I leave my main hydration solution, be it nalgene bottles or a reservoir, at the hotel. I then fill up this bottle which is much more comfortable for edc use