It's in a future update, it should be in the desert however until you can find the desert kings or whatever's temple/pyramid you won't get access to the spring.
I knew it would be the desert, that is 1 clue to start with the springs location and another clue too, the pyramid is the place we can find the ancient spring at the heart of it, probably better watch out for traps and other dangers inside protecting it. Desert King means Pharaoh right, all of you know what I mean. We'll probably find the monster responsible who'd cursed bell and the others who suffered.