Bring 4 cups of water barely to a boil. You can do this on the stovetop, or you can heat the water in the microwave for about 6-7 minutes. Add the tea bags and baking soda to the hot (but not boiling) water and steep for 4-5 minutes.
Whisk sugar into the hot tea until the sugar is completely dissolved.
Pour tea into a gallon-size pitcher. Add 3 more quarts (12 cups) of water to the pitcher; stir.
Refrigerate for at least 4 hours, or overnight. Pour over ice and serve with lemon wedges and fresh mint, if desired.