Say it just rained recently. (I know it doesn't, but just bear with me, okay?) You're out in the woods collecting... well... wood. Suddenly you run out of stamina!

I suggest that we have puddles be foragable in various types of terrain, and when picked, would fill 5 liters into whatever containers you were holding at that time.
Along with this suggestion, I present to you...
Rain Collectors
Basically just a tub that would be built out of clay or brick/other materials that would slowly collect water over time.