Watermelon Aguas Frescas

5 cups watermelon, cut into pieces and seeded
1/2 cup granulated sugar
1/4 cup fresh lime juice
3 cups water or club soda
1 In a blender, blend watermelon with sugar.
(If you weren't able to get all the seeds out, strain into a pitcher.)
2 Add lime juice and water of your choice.
3 Add more sugar to taste.
(I prefer this to be a refreshing drink so I generally won't add more)
4 Garnish with limes or fresh mint.