No, it's not really water. It's a clear, glossy product known as "Mod Podge". It goes on white, looking sort of like Elmer's Glue, but it dries perfectly clear.
When wet, it's thick enough to work a little texture into the surface. Instead of a smooth glass-like surface, you can create the look of moving water.
It takes a few days to dry completely. The thicker the layer, the longer it takes, so try to stick to thin layers.
