In a large saucepan, bring 4 cups water to a boil. Stir in sugar until dissolved. Remove from the heat; add tea bags. Steep for 5-8 minutes. Discard tea bags. Add 4 cups water. In another saucepan, bring raspberries and remaining water to a boil. Reduce heat; simmer, uncovered, for 3 minutes. Strain and discard pulp. Add raspberry juice to the tea mixture. Serve in chilled glasses over ice. Yield: about 2 quarts.