|I still have some Lipton|
The fastest way to make Iced Tea is to boil water, brew tea a little strong, and add lots of ice. This is fine, but it lacks a depth of flavor. For that, you need a longer brewing time.
I grew up with Sun Tea. You add one tea bag for every pint of leukwarm water and set in the sun for 3 to 4 hours. If you want to pre-sweeten the tea, you can do that when you pull the tea bags and the water is still warm, stir everything together, and refrigerate. Any flavor of tea works, but we always used basic Lipton because it was the '80's and no one knew of any other tea besides Nestea, Lipton, and the green tea you got in Chinese restaurants.
Cold-brewed Tea takes considerably longer than Sun Tea. It is also best to use loose-leaf teas instead of tea bags, so the leaves have plenty of room to expand and infuse the mix. Use 1 Tb of tea per pint (or whatever is 1-1/2 times what you normally use). Place cold, filtered water and leaves in a container, close the lid, and let it rest in the fridge for at least 12 hours, and as many as 24. Strain out the leaves before serving.
So why plan a day ahead for Cold tea instead of the Sun version? It's less bitter and contains less caffeine than any warm-brewed tea, as both qualities require heat to separate into the infusion. There's less chance of any stray mold or bacteria from the leaves growing and becoming part of the tea.
Does that mean that Sun Tea is on its way out? Not by a long shot. It will always exist, for no better reason than it does not require any electricity or gas to make. It is a solar-powered drink that you can make while camping, if the power goes out, or you're spending the afternoon on the porch and want something to look at besides a TV. The bitterness is part of its charm, and speaks of that homemade quality. It's just traditional. As for the bacteria issue, that is why you don't leave it out longer than four hours. If you brew it without any sugar in a freshly washed jar and use filtered or bottled water, the odds of a tainted batch are infinitesimal. It also helps if you only make as much as you plan to drink in a few days.
Now that I've had my say, it's time for you to start thinking about which kind to serve at your 4th of July picnic!