- 8 cups cubed watermelon (seeds removed), or 1 quart watermelon juice
- 1 cup freshly squeezed lime juice
- 1/2 cup sugar, or more to taste
- Lime slices, for garnish (optional)
- Place half of the watermelon cubes in a blender and process until smooth. Strain through a fine-mesh sieve set over a large bowl; discard the solids. Repeat with the remaining watermelon cubes. You should end up with about 1 quart of watermelon juice.
- Add the lime juice and sugar to the watermelon juice, and stir until the sugar has dissolved. Taste, and add more sugar if necessary. Transfer the limeade to a nonreactive pitcher and refrigerate until thoroughly chilled.
- Serve over ice in tumblers, with lime slices for garnish.