Pour the two cups of water into a large saucepan and bring to a boil.
Add the tea bags and remove the saucepan from the heat. Cover and let the teabags steep for 5 minutes in the boiling water.
Squeeze the tea bags to release as much liquid as possible and discard.
Stir in the sugar.
Cool to room temperature. Then refrigerate, covered, for at least 2 hours.
When ready to serve, add additional lemon slices into two cups (with a lemon wedge on the side of the cup), or into a large pitcher. Pour tea over top. Enjoy cold!