Is there a way to script perfectly cubic "smooth terrain" water?

I'm aware that the phrase may sound oxymoronic since the whole point of smooth terrain is to provide terrain that isn't voxel-like, but is there a way to get perfectly cubic smooth terrain water? I tried using :FillBlock(), but the results were underwhelming, and I couldn't get the blocks under a certain size. Is there anything I can do, or will I have to create my own water?

Edit: This perfectly-cubic terrain needs to be created via script.

There is a plugin called "Part to Terrain" which can turn any part into a type of terrain that might help