http://www.wikihow.com/Make-Sun-Tea
Tips:
It's recommended that you do this with caffeinated tea rather than herbal teas. The caffeine helps combat bacteria, but only for a few hours.[1]
If you are concerned about bacteria, the same thing can be done in the refrigerator, but it takes at least 8 hours.
Try adding a few stalks of fresh mint leaves and/or a few slices of lemon for added flavor. Fresh lemon balm leaves will also work.
Add a frozen store-bought container of lemonade to cool the drink and make lemon iced tea.