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.
Most are carnivorous, preying on small mammals, birds, insects and insect larvae. Some, such as iguanas, are herbivorous. Reptiles have scaly skin which keeps their body from drying out. They also have a double loop circulatory system which gives fully oxygenated blood to the body.