I don't know if this may be some weird chunk loading glitch or something, but the water in my survival world's stone generator disappeared, and was not replaced by cobble or stone, so it wasn't destroyed by lava, as seen by the picture. I am in a drought custom world, that may affect it (although I don't think that should affect anything except terrain generation), but if this is something that seems to never happen under any circumstances, it doesn't really affect much other than having to find one of my misplaced buckets.