Preparation Additional ice cubes (for serving) Puree cucumbers, ice, grapes, water, and lime juice along with 10 mint leaves in blender. Strain. DO AHEAD: Can be made 6 hours ahead. Cover and chill. Fill 6 glasses with more ice; pour agua over. Garnish with additional mint sprigs.
Preparation Additional ice cubes (for serving) Puree cucumbers, ice, grapes, water, and lime juice along with 10 mint leaves in blender. Strain. DO AHEAD: Can be made 6 hours ahead. Cover and chill. Fill 6 glasses with more ice; pour agua over. Garnish with additional mint sprigs.