Revit does not have any built-in tools for modeling water, though I have previously shown how you can Model Water with Topo. But this method is more of a workaround and it does not work particularly well in section.
Now with Dynamo geometry tools and a couple of nodes from Spring Nodes, you can create a solid water element that perfectly follows your Topography.
This definition is based off a method I first saw on Revit Dynamite and Ammo, Cutting Objects to Topography. It requires several inputs. First, an extended boundary of the water area (a simplified boundary that is larger than the water). You also need to specify the water elevation and extended water depth (again, a value greater than the depth of the water).
When working with large and complex Toposurfaces, you might need to split the surface to create the water solid. I had a few issues trying to create this water. The Geometry.Split node should return two solids; if it only returns one, try working with a smaller surface.
Here is the result in Revit:
Because Topo is a mesh, a water solid that is cut with Topo will also have triangulated edges. This is visible in plan if the water has any transparency.
If this is a big issue, you could try converting your Toposurface to a NurbsSurface before splitting the water solid. But the water will not perfectly follow the Topo in section.
You can also create water geometry along architectural surfaces, such as walls.
It just requires a few more nodes:
And finally, even though the family will not give you a volume parameter for the solid, you can easily find the volume by creating a Material Takeoff schedule