To get Soph to accustomed to using a water bottle, I had to smear a little bit of banana on the end.

Piper, *USE* to be great with his water bottle and then he flat out refused it--he'd wait till his nightly romp and then drink from K'Cee's bowl. I bought a bowl that hangs on the cage and he LOVES it. (I still keep a water bottle in his cage just incase the bowl should spill.)

Bunnies are not nocturnal. I can't remember the correct word but they are most active in early morning and early to late evening. Watch his habits and see if he fits the pattern. I know Piper eats/drinks the most during these times.

You might try Willow with a bowl and see if he likes that better. And for peace of mind you can always do the "hydration" check. (Pinch/pull up some skin -- if it snaps back, he's fine!)