I was in your shoes once and started offering diluted juice - I mean REALLY diluted fruit and veggies juice, with the lowest sugar content i could find. This is what he drank for the past year. Well, I am sad to say that it was staining/ decaying his teeth. When the dentist explained to me that it is like a baby walking around drinking a bottle all day, I felt like an idiot, because obviously I wouldn't do that. I explained that he wouldn't drink anything at all and she said he will drink when he is thirsty. It took a couple of days for him to really drink water, but she was right. Now he asks for it.
My point is, I wouldn't offer juice at this age. i learned the hard way that it was a bad idea. Fortunately, M's teeth are fine after a cleaning, but if I hadn't gone, he probably would have gotten a cavity. He is also the most stubborn kid I have ever met and did give in to drink water when he was thirsty.
This time around with my 2nd LO, I am sticking to water.