Water Y-coordinate

Water in Minecraft is always at Y62 coordinate like sea rivers and lakes all of those are in Y62 coordinate, the only water that doesn't go to Y62 is cave waters, so why not change the water Y62 coordinate to a higher and lower Y coordinates, like Connect water Y64 to Y62 waters, so that it will create small water flow, make a river coordinates higher to Y73 then go down to Y67 and go down to Y62 it will generate waterfalls, make Y62 waters connect to cave water Y53, I don't know cave water coordinate so I put Y53 :], make one-block water streams, also what I mean by waters is rivers and if the water will go down to Y67-coordinate to Y62-coordinate it can be to a river or a lake :D,