I wrote about the Decanter of Endless Water being canon before and the consensus is that it was a mistake.
Is it possible that a Decanter of Endless Water exists on Athas as an artifact? I think it’s quite likely that it does. It has a “curse”. It’s not really cursed, but whoever holds it tends to get killed by people wanting it for themselves.
Perhaps the Decanter was held by the city of Kalidnay before that city’s sudden collapse. After that it disappeared, occasionally reappeared, each time bringing chaos and destruction in its wake.
Recently the decanter has been rediscovered, the source of water for a desert oasis. This has sparked “the war of the wastes”, with slave tribes, elf nomads, gith hordes, belgoi manhunters, thri-kreen clutches, dwarven clans and more all duking it out for the Decanter, with the Decanter changing hands every couple of days. The PCs are tasked by the patron to recover the Decanter.
Of course, even if the PCs manage to get the better of these rival groups, they will be up against the clerics of water, who believe that the Decanter is a holy relic of their religion and that it must stay in their hands. Even more dangerous than the clerics are the Sorcerer Monarchs, who would see the Decanter set up in their own city-state like it was in Kalidnay.
The Decanter would be an immense boon to the owner that can afford to protect it, but it would hardly change the fact of general water deprivation on Athas. Any ideas?