To make 1L:
Take 6 heaping teaspoons of loose leaf tea and add to a large tea pot - add boiling water.
Steep at least 5 minutes.
Quarter fill serving pitcher with cold water.
Pour tea into pitcher while straining the tea.
Add ice - garnish and/or sweeten to taste.
To sweeten you can make a simple syrup by boiling water and sugar together and add to your iced tea separately OR simply add sugar to the tea while it is in the pot so it dissolves easily.
You can adjust and customize these steps according to your tastes.