We are looking at this too. We would want little children to be able to sit and play so our max I think should be 10 to 12 inches. We plan to install a water shower over the area as well as a large umbrella ( we live in Florida). I too would like to hear what others have to say about water temp and depth in this area. It it were just for adults I might go to 16 inches.

Remember that the steps need to be uniform in height. 8” to 10” is good.