Some background for you in case it is news, as this was a hot topic of discussion in the A21 release about a year ago...
None of the other consumables has a container. Gasoline, for instance, the gas can icon just represents the liquid, not a container. So, water is just depicted as a glass jar but they're not really trying to have a container that gets filled. Thus, while the "empty glass jar" was what we had, the issue of carrying around water doesn't really depend on having empty jars.
Instead, I focus on the ability to carry water away from a water source. If the game is just going to assume containers are always available for things like gasoline, then to me the assumption is also true for water. Thus, I think the best outcome is that when you're at a lake, you should be able to drink (currently possible) or carry away some water which would look like a jar of water.
However, TFP wants some early game survival challenges and struggling for potable water is part of that. I can embrace the goal. I love the goal, actually. I just don't share much enthusiasm over the implementation. They would have you go into POIs and find water as loot, and that is currently a viable method of play. Once you find a cooking pot, this quickly evolves into purifying the water you find. Once you get a little knowledge about workstations (2 magazines) you unlock a Dew Collector which produces water. Over time, you'll likely develop a number of Dew Collectors (and improve the features of your existing Dew Collectors) and eliminate water scarcity from your challenges.
It isn't a bad minigame once you know how to play it. Its just that they way they deal with water sources (pools, lakes, rivers) and the initial sources of water (POIs) isn't realistic enough to align with a player's real-world experiences, so it is confusing.