one thing you can try is mio (or the walmart imitation version which is half the price) its just flavoring, pretty much nothing else to it. add a thimble sized squirt to a bottle of water and you get all the benefits of water but with taste.
Diet Soda is PURE FUCKING EVIL!!!!!!!!!!!!!!! I had a 25 year addiction to Diet Pepsi, it was the only thing I ever wanted to drink and could drink GALLONS A DAY. Now I have Parkinson's. Not sure if there is any correlation or not. You know how some people say they can't drink alcohol because if they have one drink they won't be able to stop??? It's like that for me and Diet Pepsi. If I were to have one bottle, within a few days I would be drinking it non stop. Regular soda is bad too, with all that sugar and corn syrup. In fact sugar and sweeteners in general are all evil and toxic. I never drink soda now. I drink water, beer or coffee with a little cream but no sweetener.