Water is life.

Water is sacred.

Water is everything.

Out in the dust, life is dry in more ways than one, but most importantly in the literal sense. Yours is a world of wastelands, of sand and searing heat, with so little shade that people dig and build underground to find the cool embrace of darkness. It's a hard life, made harder by the fact that water is precious—sufficiently so that it's the only form of currency you know. Nothing has greater value than water, so it's traded for labor, for goods, for services, for whatever.

There are no places where water gathers in great amounts, and so you mostly have no words or names for such concepts. The stories you know of Osham describe the god of death as riding a "boat"—sort of like a wagon meant to go on water, although you've never seen enough in one place to really imagine how that could possibly work. So, the idea is there, but the reality is...distant. Fantasy. Harsh.

Harsh realities are the only kind, when you lives in the wastes. In the absence of abundant water, most moisture comes from plant life: You eat whatever fruits and vegetables you can find in order to stay hydrated, and most food (including meat) is cooked fairly rare to preserve its stored juices. Whenever possible, and especially when leaving town to herd quickhorns and so on, everyone carries a skin of water with them. This is sipped minimally, with even children taught how to ration and conserve. If a skin runs low, then foraging for ripe berries, chopping into a cactus, and the like become critically important skills; no one wants to be caught out with no water left, at all, so saving those last few mouthfuls is of paramount importance to laborers and ranchers.

Because water means so much, there are numerous traditions and taboos surrounding it that have nothing specifically to do with drinking it. Mostly, these have to do with sharing it (or refusing to do so) and what that means, but there are more than a handful of more mystical superstitions, too. An example of the former is the simple act of offering a drink to another, which demonstrates hospitality beyond simple courtesy; generally, most folks are presumed to have their own water, so freely giving them some of yours indicates trust, a desire to impress, or possibly even an apology, depending on the context. Most such customs are heavily reliant on circumstance—giving someone a drink from your waterskin when they aren't your guest, for instance, can indicate affection for them, potentially equivalent to flirting. More overt would be the act of bathing another: This is something typically done for children by their parents, or on the other end of life, for parents by their children when elders can no longer wash themselves. In either case, this is typically a perfunctory ritual, as the absolute least amount of water manageable is spent on hygiene. Were a woman to offer to bathe a man outside this dynamic, however (or vice versa), it would be a heavily intimate thing, particularly if she were to be lavish with the water. In fact, this is a common rite performed on wedding nights.

Regarding the more phantasmagorical side of things, it's treated as bad luck to leave water out in an unsealed container for any length of time. Probably this has its roots in the way heat causes water to disappear when untended—something everyone knows will happen—but it's entered the collective consciousness as something slightly more sinister. A few people might even claim it's a punishment from the gods for mistreating such a precious resource. Likewise, water spilled by accident, especially on the ground, is interpreted as a sign of coming misfortune; everyone is so careful with the stuff, dropping any must bode ill. To deliberately pour water out is unthinkable, not even used to punish someone for great wrongdoing, and so it is only assumed to be done as a component of harmful witchcraft—basically, doing something evil in order to conjure further evil.