Measure peanuts into a container and cover with filtered water. Allow to soak overnight. This softens the nut and makes it easier to blend, leaving less particles of nut in the finished milk (plus you get some of the benefits of soaking nuts too!).
Drain nuts and place in a blender. Add 4 cups of filtered water and blend until smooth, approximately 1 minute. Store in the refrigerator and enjoy cold.
For two cups: 1/2 cup peanuts, 2 cups water For one cup: 1/4 cup peanuts, 1 cup water