water does seem to be a stumper when it comes to chams. Everyone's seems to have different habits. I have had Luna for nearly a year and although she has been offered a dripper many times (days on end) it wasn't until after she laid her eggs has she gotten in to a routine - thank goodness! I tried the dripper in a few different places this time around and we have both settled on the far back left corner. In the morning, once she sees me, she goes right back there and looks up until I have turned it on. Then she just sits under it and the water rolls down her face. Since she has that funny crooked mouth the water just sort of slides right into it! LOL!
I recently worked out a good humidifier setup. It's on top of the cage on a board and I aim it at the ceiling (covered with a piece of plastic so I don't mess it up) and I also have a plastic mat set upright so the water is confined and doesn't land on my MV bulb/fixture. it works great b/c it just pours into the cage and Luna has made it clear that she really likes it, too! Sometimes I enclose the cage with the shower curtain and the humidity goes up to 90%. then I let it come back down. I will take pix so this makes sense. the point is....yes, there is one....that with the humidity being better regulated I don't worry nearly as much about her hydration.
I have almost never seen Luna drink per se, like off a leaf, but if it is rolling down her face she sort of sucks it in - yours may be doing that, too. How does his urates look (color)? and are his eyes nice and buggy?
sorry this was so damn long! ;-/
lele
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0.1 veiled - Luna
0.2 house geckos - Gaia & Tia (MIA 
0.2 felines - Kyndra and Líta