The client for this project prefers the softer look of watercolors over 3D. So I ran the rendering through the watercolor filter in Photoshop.
I like what it does to the people and water but not so much to the floor and walls.
What do you think? Can you suggest a better watercolor technique?
Btw, splashing water is a photo composite and trees are Bionat.
-Greg
Original Render:
I think the filter version looks pretty good mate. The only thing I would do is add the reflection of the waterfall to the pool.
Greg,
I think what you have done looks good. One thing I think always helps when trying to implament a more "painterly feel’ to your 3d renderings is to increase the canvs size in photoshop and paint over the edges with a textured brush to help eliminate the hard edge of the rendering.
I hope you don’t mind. I took your image into photoshop to help illustrate my point. Good Luck!
Try using a couple of layers with different filters applied to each then adjust the opacity and/or blending mode. I found using a sponge filter gave me a nicer result than watercolour sometimes.
I also tended to overlay the original image again at around 40% screen or overlay to bring back a little of the sharpness to the details.
Basically, mess around with more layers. 
Great result, have you tested piranesi ?
Looks pretty cool 
I like the textured edge! I’ll use that idea.
I’ll also try the overlay technique.
I’ve tried Piranesi a couple years back but couldn’t justify the cost and time to learn it then. Maybe worth a second look.
Thanks,
Greg
How exactly did you compose the splashing water?
Its a tough one. It seems a pity to use a filter over the top of what seems to be a good image.
Try muting the colours a bit and reducing all that black edging that Photoshop always seems to add.
The waterfall was composited from a photo of a similar water feature.
It was pretty easy to separate the white water from the background in Photoshop using the color select tool.
Great work!