[Sardtok]

To actually get the curvature of the water against the glass?
I don't think I've ever seen that in 3D images, the reason the split looks like that is because the water curves up against the glass.
Usually in 3D I think I've only seen clean splits, and none that mimic the physical attributes of water (the bipolarity and the effect it has on the surface, not sure what you call that tension in English, in Norwegian it's just surface tension).
If you are just doing a single picture, you could model the water like that, though I've never tried it, so I have no idea if it works.