Here's The Tea Centre's recommendation on how to make iced tea:-
Ice Tea
Any tea can be made iced, but fruit infusions and flavoured teas are exceptional as they make a great natural and refreshing drink ideal in the warmer months and a great thirst quencher.
• Generally you will need approx 1 tablespoon of tea or Infusion per litre of water.
This will depend on the leaf size.
• Use cold water on tea leaves as hot water will increase bitterness.
• Leave in fridge for at least 4-8 hrs, but for best results leave overnight.
• Serve over Ice, add lemon or citrus slices, fruit or mint leaves.
• Add a little honey or sugar syrup as this brings out the fruity flavour.
• Sugar Syrup – combine equal parts sugar and boiling water., stir until dissolved.