To add some secondhand experience to this thread: a former roommate of mine (before I met her) had to have surgery on a kidney stone. The doctor told her and her mother that her iced tea habit was to blame - several glasses a day with no other liquids. If I recal, the word "polypheonols" was mentioned and then there's the caffine being a dieuretic besides. Edit
: Not polyphenols but oxilates. Google tea and kidney stones and you'll find that tea is a major contributor to oxalate levels but no source recomends you cut back on it unless a doctor says you should. (Coffee, chocolate, spinich and strawberries were among the list as well as a few others.
I don't know what kind of iced tea she drank though it likely wasn't fancy - when I saw her drink hot tea it was usualy bagged jasmine or green. Might have been bottled tea, might not have been. But I think the key in this case was the "no other liquids" part. If she'd been drinking water as well it probably wouldn't have been a problem (and she would get bottled water delivered by the case to our appartment).
So the lesson is that tea shouldn't be the only part of your fluid intake - my 2 to 4 cup a day tea habit gets well supplimented with my favorite flavored seltzer water that I often drink by the liter bottle (Polar brand if you live in the northeast US...their flavors include vanilla and pomegranite). (IMO, drinks that count torward your water intake should be non-cafinated and minimaly sweetened if at all...so herbal tea counts!)
By the way...Alton Brown did *not* recomend distilled water...filtered was mentioned in the eposide but not distilled, and he recomends against it for other things like coffee.
Link to a transcript of the tea episode.
Why yes I am a fan...