In my personal and professional opinion, the proper way to make iced tea is by cold steeping. Making hot tea and cooling it down will nearly always warp the tea’s flavors, lose much of its sweetness and bright aromatic notes, and result in a cloudy astringent drink that is anything but refreshing – this is why most iced tea will use a traditional cheat, such as baking soda or boiling water, or be heavily sweetened. To me, iced tea must be, above all, refreshing. Cold steeping is the best way to achieve that.
Unlike bottled iced tea, homemade iced tea has no chemicals in it to keep it “fresh” for an unnatural amount of time. You should drink your tea within 2-3 days. Never continue to drink tea that develops an “off” flavor or exhibits any bacterial growth, usually visible as a thin film on the surface of the tea.