Place nuts in a medium sized bowl and cover with water to depth of about 1 inch. Let soak overnight or for up to 2 days ; the almonds will puff up as they absorb water.
Drain and rinse the nuts and transfer them to a high-powered blender, along with the filtered water, vanilla bean (or extract) date, and salt. Blend on high speed until the nuts are completely broken down, about 30 seconds.
Position a medium bowl under a nut milk bag and pour nut milk mixture into the bag. Holding the top of the bag shut with one hand, use the other hand to squeeze the almond milk from the pulp until it's dry (if desired, reserve pulp for another use; it will keep in an air tight container for up to 4 days). Taste the milk. If it is not sweet enough or if the flavor needs to be adjusted, pour the milk back into the blender and add more date, salt, or vanilla to taste. Makes 2-3 cups.
Nut milk will keep (covered) in the refrigerator for about 5 days. Separation will occur. Just swirl the milk around before using.