Place the watermelon chunks into a blender, ensuring they're evenly distributed for smooth blending.
Add the fresh lime juice and salt to the blender. Secure the lid tightly.
Blend on high speed until the mixture is completely smooth, about 30-40 seconds. You should see a vibrant, uniform pink liquid with no visible chunks.
Pour the blended mixture through a fine-mesh strainer into a large pitcher, using a spatula or spoon to press the liquid through and leave the pulp behind. Discard the pulp or save for another use.
Chill the strained agua fresca in the refrigerator for at least 10 minutes. When ready to serve, fill glasses with ice cubes and pour the chilled beverage over the ice.
Garnish with a lime wedge if desired, then serve immediately for a refreshing, cold drink.