What is your humidity at? What are you using for heat? About all you can do is add more holes, find a smaller water dish and clean up after any water spills. If you are using the lid that came with the tub drill some holes in the top. Maybe you can try a different substrate too.
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Tosha 
"Stupid is forever, ignorance can be fixed." Don Wood
"Of course, that's only my opinion...and I believe I am God." =) Chris Bianco
7.33.0 Ball Python (Harry and Fluffy and gang)
1.0.0 Angolan Python (Skywalker)
0.0.1 Green Tree Python
0.2.0 Feline (Pippen and Pandora)
0.0.1 Dessert Tortoise (Pope John Paul)
2.2.1 Fish (1,2,3,4)
0.0.0 Pool skimmer rescues for this season