It has to be shallow mine is no deeper then 2 inches as I do have some Juvie's in with my adults. You don't want them to flip over and drown. I'll post my outdoor enclosure here so you can see I use the bottom of a dog igloo house for the water reservoir. Also have a sprinkler head in the enclosure and they love it. Sorry it took so long to get your question answered as I don't check this forum much...later Rich

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Richard -amazoa-

"Changes in behavior occur when the pain of staying the same outweighs the pain of change."