DEHYDRATION
Water is a survival stat. Ignore it and you die.
The Dehydration mod adds thirst to the game: just like food, you need to stay hydrated to survive and thrive. You get a thirst bar next to your hunger bar, and it drains as you play.
Water sources, wells, and carrying something to drink on expeditions are real logistics. Settling somewhere without reliable water is a strategic mistake. For the practical details, containers, purifying, and which foods hydrate, see water in the main wiki.