Fill a large pitcher with 2 quarts of cold water. Quarter orange, squeeze juice into pitcher as well as add the peels. Pit and cut plums into wedges and add to the pitcher. Cut the strings off the tea bags and mix the bags into the liquid. Let tea steep in the refrigerator 8 hours or overnight, stirring occasionally.
When ready, remove orange peel and tea bags from pitcher. To the tea, stir in sugar until it dissolves. Cut the lemon in half and squeeze the juice from 1 half into the tea. Slice the other half into rounds and add to the tea. Serve over ice.