Bring 4 cups of water to a boil over high heat in a saucepan or electric kettle; add tea bags and brew for 15 minutes.

Mix in sugar and baking soda. Pour mixture into a gallon pitcher and add 12 remaining cups of cold water.

Optionally, slice a lemon in half and squeeze into the tea with your hand underneath to catch any seeds. Drop the used lemon halves into the tea. Refrigerate.

Serve ice-cold and enjoy!