I've had kidney stones (a lot of them in one kidney, causing much pain) that were removed by lithotripsy. The doctor told me to avoid tea and to drink a lot of acidic drinks like real lemonade. I still have stones in my other kidney but they don't bother me.
I have heard that drinking water and vinegar works to break down kidney stones- only heard that this week, so thought I'd pass it on... have no more info about it than that, though...