I know I've seen plenty of other recipes out there for aguas fresca,"fresh waters" so if you read food blogs and you haven't made them yet, I probably won't convince you to try.
They're super tasty. I personally never liked cantaloupe until I tried it as an agua fresca. The melon/lime combo works amazingly well. I consider my first taste of agua fresca to have been a life-altering event.
They're refreshing. Because the fruit used to make them isn't quite as sweet as orange juice and the puree is further adulterated with water and lime juice, they don't leave you with that cloyingly sweet mouthfeel you sometimes get with OJ, but they do linger longer than a gulp of iced tea.... and they'll actually cut the heat of spicy foods, which makes them perfect for a fiesta.
They're interchangeable. The ratios work with any melon you want to try. Watermelon is another personal favorite [and who hasn't bought too much watermelon at some point and had an awkwardly-shaped hunk o'leftover dominating their fridge?]. In the height of summer, when grocery stores get all those different varietals (musk, tuscan, canary... etc.) you can explore the various flavors via fruit drink and not feel like you're eating melon _all the time_... and then you can try various melon medleys! The fun never stops!
Recipe: Agua Fresca
If your melon is tasteless, your drink will be, too. Sniff the stem end of the fruit before you buy; it ain't ripe if you don't get a whiff of fruit. It's easier with most melon if you just scoop out the seeds, but you can puree the flesh with the seeds and pulp and strain it through a fine mesh sieve... and that's the easiest way to do watermelon, unless you have a food mill.
Sugar, Honey, or Agave Nectar
Ice and Lime Wedges, for serving.
Puree melon in a blender or food processor until smooth, or press through a food mill. For each cup of melon pulp, add a cup of water, a tablespoon of lime juice, and a tablespoon of sweetener. Adjust lime or sweetener to taste. Serve chilled, over ice, with a wedge of lime.