I am going to have to put this on my project list. I have been looking at some cool larger water skins on Etsy apparently made similar to this. The person who makes them is going for Viking period, and makes them up to at least 2.8 Liters. Those tend to be longer and curved for carrying on your side on a long walk.
Does anyone on here have a reference for waterskins like this that places them in America in 1800-1840? There are lots of areas out west that are plenty dry. The mountain men and explorers would have carried water at least some of the time, if they had the ability to do so, and the technology to do so had been in existence for hundreds of years.
To me, this is similar to arguments I have seen that suggest a mountain man would have needed to have served in the military to be familiar with military issue equipment like backpacks that have 2 straps. I lean towards "The mountain men were not idiots. If they saw someone with a good idea, they may have copied it." So, I acknowledge that they got mighty thirsty on some of their travels, but they would have tried to carry water at least some of the time when crossing areas without ready water. Canteens were common military equipment in the united States before and after the fur trade period, so many of them would have been familiar with the concept.