I can't seem to find a diagram on how deep reflection pools usually run, the one in DC is only 18" deep but at the Twin Towers they quote 30'.
How deep is deep?
How deep is deep?
I imagine depth depends on how each reflection pool was designed.
At the Oklahoma City Bombing Memorial there is a reflection pool. I have never seen a depth listed just "shallow" and it is - it appears about as deep as an average puddle.