Of course you are. I am only joking.
A water garden is a garden in which water plays a dominant, or, at least, a major role
In my own Japanese Garden there is a large pond of approximately a quarter acre. Within this there is a water fountain, and, of course, a waterfall
I also have a 'shishi odoshi' which is the famous Japanese Deer Scarer, a small bamboo waterfall, and a bamboo rill flowing into a 'tsukabai' in my Tea Garden. There is also a Tea Master's well.
All in all, although my garden is most definitely intended as a 'Japanese' garden it is also a 'water' garden
This is my waterfall