I've often wondered, how do you stop it from going bitter and yucky? If I make a cup of hot tea and let it go cold, it's not very nice. Actually it happens to me practically every day at work and I just tip it out. No-one I know is happy to drink hot tea that went cold accidentally. So how do you make it different? Is it in the teas used, the chilling process or maybe in the brewing temperature?
I think some of it is the variety of tea used, and some of it is the method for making iced tea.
Iced tea in the US tends to be made with Lipton
(or similar). It's a blend of tea that, according to their website, is Orange Pekoe and Pekoe cut black tea. The method that I am most familiar with is to either make hot tea, and pour it over ice before it has cooled all the way, or to make tea in a way that doesn't involve heating the water at all (sun tea or just cold-brewed tea).
When you pour hot-brewed tea over ice, it tends to get a little more diluted as the ice melts, and that helps keep it from getting bitter. When you brew tea without using boiling water, the acid content is lower, which helps with the taste.
One other thing I'll note is that most of the tea-drinking countries I'm aware of tend not to drink Lipton-style tea varieties. When I spent a semester in Ireland, the tea that was sold as just generic tea (usually in enormous quantities) was actually Irish Breakfast tea. Something like that, or English Breakfast, or Earl Grey, taste very
different when iced than what you'd normally find in the US. I personally think they all taste terrible iced, no matter how you prepare it.