1. Bring the water to a boil in a large saucepan.
2. Add the tea and remove the pan from heat.
3. Stir to submerge all the tea leaves in the water.
4. Steep for about 5 minutes.
5. Pour the brew through a coffee filter or a fine-mesh strainer into a large pitcher.
6. Add the sugar to the hot tea and stir to dissolve.
7. Cool to room temperature.
8. Cover and refrigerate until ready to serve.
9. Fill tall glasses with crushed ice.
10. Add enough of the tea to fill the glasses to within 1 inch from the top.
11. Then float 3 to 4 tablespoons of evaporated milk over the ice in each glass.
12. For a taste of the west, include a half-and-half creamer with, or instead of, evaporative milk

How they do it in Bangkok: Traditionally the tea used to make Thai Tea (Cha Yen) is a black tea grown in the northern hills of Thailand. The tea is placed in a strainer and boiling water is poured over it 4 or 5 times. The tea becomes a muddy red color and is VERY strong. The tea is poured into a plastic bag over lots of ice, sugar-water syrup is added, evaporative milk is poured over the top, a straw is inserted into the baggy and you are handed your personal package of yummy Cha Yen.