Put the rice, 8 cups of water and salt into a large pot. Bring the water to a steady boil using high heat.
After boiling, reduce temperature to low and simmer for approximately three hours, or until the rice is mushy and falling apart. I often leave this on my stove for 4 or more hours with no negative side effects. **Note: Leave the lid on for the entire cooking process. You don't want the water to evaporate and then all you're left with is mushy rice.
Let the liquid cool somewhat before adding it to a blender. Add any optional ingredients and puree several minutes until rice has become completely liquid. I usually strain the bigger pieces out of the liquid first before running it through the blender.
Transfer to a large container, and add 1 cup or more of water to thin out the consistency a bit if you like your rice milk that way.
Keep refrigerated and stir before each use. Unsure as to how long this keeps in the fridge, but we've used it up to a week after making it and it still tastes wonderful.