In a small saucepan, combine 1 3/4 cups of sugar and 1 cup of water. Bring to a boil and stir to dissolve sugar. Allow to cool to room temperature, then cover and refrigerate until chilled.
Juice enough lemons to make 1 1/2 cups of juice (approximately 6 large lemons.)
Place mangoes in a blender and puree until smooth.
Combine pureed mangoes, lemon juice, sugar water, and remaining 8 cups of water in your pitcher and stir. Add ice or serve over ice for a nice chill.