Add the coconut water, coconut milk, cold water, fresh lime juice, lime zest, and sweetener to a blender.
Blend for 30 to 45 seconds, or until smooth and creamy.
Taste and adjust the flavor with more lime juice for tartness or more sweetener for sweetness.
Strain through a fine mesh sieve if you prefer a smoother, lighter drink.
Fill glasses with ice.
Pour the coconut lime agua fresca over the ice.
Garnish with lime slices, fresh mint, or shredded coconut if desired.
Serve immediately while cold.