Wash the rice and place it in a bowl. Cover with water (water lever should be an inch above the rice), and soak for at least 2 hours to overnight.
Drain the soaking water and place the rice in the blender along with 2 cups of water and one cinnamon stick. Blend until well combined. Strain the mixture into a large measuring cup or pitcher.
Pour the strained mixture into a pitcher and mix in the sugar, milk, and remaining two cups of water. Stir until the sugar dissolves. Add ice and serve cold!