To me, as long as you're drinking a bottle of water with it I see no harm. You get hydrated from coffee. Of course you need to drink water in general, but the concept of drinking cups of water to balance out dehydration from coffee is just a myth.
Reptiles do not maintain their own body temperature within a narrow range like mammals and birds, so controlling their environmental temperature is critical for normal activity and good health. Reptiles are poikilothermic-which means that their body temperature alters with the surrounding environmental temperature.
Have you ever seen a gecko without a tail and wondered why? Lizards and other amphibians can lose their tail at-will and have the ability to regenerate and grow new ones. But why do lizards lose their tails in the first place and how are they able to grow back?