Use a knife and cutting board to peel any rough skin from the watermelon and cut into 1-inch chunks. Measure out 4 cups of watermelon chunks.
4 cups watermelon chunks
Place the watermelon chunks into a blender. Add freshly squeezed lime juice and sweetener if desired. Secure the lid tightly.
4 cups watermelon chunks, 2 limes lime juice, to taste sugar or honey
Blend on high speed until the mixture is smooth and uniform, about 30-45 seconds. Check for a consistent bright pink color with a slightly pulpy texture.
Pour the blended watermelon mixture through a fine mesh sieve into a pitcher, using a spatula to press out as much liquid as possible, leaving behind pulp if desired.
Fill glasses with ice cubes and pour the watermelon lime agua fresca over the ice. Garnish with lime slices if desired and serve immediately.
ice cups ice cubes