Quick soak the almonds: Add the almonds to a small pot and cover with 3 cups of water. Bring to a boil, then remove from heat and let soak for 15 minutes. Alternatively, you can soak the almonds overnight.
Drain the almonds, then add them to a high speed blender, along with the 4 cups of fresh water and maple syrup/vanilla, if desired, for slightly sweetened vanilla milk. Or keep it plain if you plan on using it for savory dishes.
Blend on high for 1-2 minutes until creamy and white.
Get out your nut milk bag, cheesecloth or even a thin clean dish towel. Over a mixing bowl or large measuring cup, strain the milk through the nut bag, gathering it up and squeezing well to get every last bit of liquid you can. Discard almond pulp, or save for using in other recipes.
Transfer strained milk to glass jugs or other airtight containers. It will keep for up to 4 days in the refrigerator, and can be frozen if needed. Enjoy!