Bring 4 cups water to a rolling boil. Stir in coffee powder and return to a boil. Remove pan from heat and set aside. When coffee reaches room temp, strain through a coffee filter into a pitcher. Add water and sugar and stir to dissolve. Cover and chill. To serve fill glasses with ice, add 3/4 cup of the chilled coffed to the glass, top with 3 tablespoons of evaporated milk. Serve.