Can you put water in a regular reptile style tank?

I just bought a box turtle, I was told at the time that he was an asian box turtle and he lived strictly on land. Later in my research on him I found out that he is a Malayan Box turtle (yes I know that is still in asia) and that they are the most aquatic box turtle you can have. Now I have this reptile tank that I cannot return and a Turtle that seems to be unhappy. Can anyone help? I have thought of maybe making a "pool" for him in the tank by adding a bowl with a ramp, but that seems almost dangerous, especially for a turtle.