Blend the watermelon: Get out a large blender and add the cubed watermelon and half of the water to it. Set it to high and blend the ingredients for a couple of minutes or until it is as smooth as possible.

Strain the juice (optional): If you like a little bit of pulp in your agua fresca skip this step. If you want it to be without pulp simply strain the liquid through a fine-mesh sieve and into a large mixing bowl.

Add sugar and lime to taste: Add the remaining 2 cups of water to the liquid, and stir to combine. Then taste the liquid and depending on the quality of your watermelon you might need to add some sugar for sweetness. slowly add and stir in sugar until it is sweet enough to your liking. Finally, add in the juice of 1 lime if you want to add a little bit of tartness to the drink.

Serve the watermelon agua fresca in a tall glass with some ice cubes and enjoy!