Step 1Combine all the ingredients in a blender and puree on high for 30 seconds to break up the rice.
Step 2Turn off the blender and refrigerate the mixture in the blender overnight, or at least 8 hours.
Step 3When ready to serve, re-blend the mixture.
Step 4Pour it through a fine mesh strainer then pour it through a layer of cheesecloth to remove any remaining sediment.
Step 5Taste and add more sugar, if you like. Serve the horchata over ice.
Macadamia/cashew/almond: Replace 2 cups of the rice with 2 cups unsalted macadamia nuts, cashews, or blanched almonds.
L.A.-style: Replace 4 cups of the water with 4 cups canned evaporated milk.
Spanish-style: Replace the rice with 4 cups tigernuts (you can purchase them online).