TBH, about the "water treatment plant". Well, when we think of water treatment plant, we think of clean water. We know the places outside of reborn city except the aphophyll area have clean water, and celesine cascade of course.
Well, on the map the water treatment plant is right next to the opal ward, to be specific the opal bridge. We have not seen or heard anything about this yet in the game, no matter how hard we try to find it we cant find it anywhere near there. But, im sure all of us have been to the grand hall, has anyone noticed that there is water there, here , and it is clean, so what does this tell you, the water treatment plant is near here otherwise how is the water here clean??