This video tutorial goes through the steps of creating a water material in V-Ray for Rhino. This process is very similar to the creation of a glass material with a few key differences and I have also included the timestamps below so you can skip ahead to specific sections:
1:05 - Creating a new material and the base settings for the water texture
2:00 - Refraction settings
2:20 - Using a noise map within the bump settings to create water ripples
3:50 - Texture mapping
4:40 - Adjusting the size of the ripples using the noise map and bump intensity
6:18 - Adding a colour tint (fog colour) to the water
8:00 - Reflection adjustments