Add oats, water, salt, maple syrup, vanilla extract and date into a high speed blender and blend for about 30 seconds. Don't over-blend because it can make the milk slimy in texture.
Pour the mixture into a nut milk bag over a large mixing bowl.
Transfer to a sealed jar and refrigerate. Shake well before use.
Notes
You can add fresh berries to make berry milk.
The oat milk keeps fresh in the fridge for up to 5 days. You know it went off when it starts to smell funny.