01 - Combine grapes, water, sugar, and lime juice in a blender container.
02 - Blend on high speed until completely smooth and frothy, approximately 1-2 minutes.
03 - Pour mixture through a fine-mesh sieve or cheesecloth into a pitcher, pressing with a spoon to extract all liquid. Discard remaining solids.
04 - Taste the agua fresca and add additional sugar or lime juice as desired to balance flavors.
05 - Refrigerate until thoroughly chilled or pour immediately over ice cubes into glasses.
06 - Decorate each serving with fresh mint sprigs or additional grapes if desired.