Preparation Puree pineapple, 1 cup water, and sugar in blender in batches until smooth. Pour into 8-cup measuring cup. Mix in 3 cups water and 2 teaspoons ginger. Cover; chill until cold, about 4 hours. Strain pineapple mixture into pitcher, pressing on solids in strainer. Add more ginger to taste. Fill tall glasses with ice. Pour agua fresca over.
Preparation Puree pineapple, 1 cup water, and sugar in blender in batches until smooth. Pour into 8-cup measuring cup. Mix in 3 cups water and 2 teaspoons ginger. Cover; chill until cold, about 4 hours. Strain pineapple mixture into pitcher, pressing on solids in strainer. Add more ginger to taste. Fill tall glasses with ice. Pour agua fresca over.