Stay away from those seemingly handy instant agua fresca envelopes: They are far too sweet, plagued with artificial ingredients, and as making fresh fruit water is no more complex than your average Hulk-green kale juice, completely unnecessary.
These recipes call for simple syrup as a way to make sweetening the beverage evenly easier, without crunchy sugar sediments. I use Zulka brand sugar exclusively in my recipes, a certified non-GMO sugar from Mexico, with a slight golden tone to it, as it is not as stripped of its natural molasses as an American white sugar. A simple syrup made with this sugar will have a beautiful light amber tone. (A simple syrup is as easy to make as the name implies: bring one part water and one part sugar to a boil in a saucepan. Stir for three minutes; the longer you leave it on the heat, the thicker it will become.)
1 cup fresh squeezed lime juice 1 cup simple syrup 8 cup cold water
2 cups fresh squeezed orange juice 1/2 simple syrup 1 1/2 cups cold water
The importance of a sturdy citrus press for these two cannot be stated enough. Buy one that is large enough to easily accommodate large limes or orange quarters. Just press, measure and mix. No need to strain.
Tuna / Prickly pear:
10 red prickly pears 1 lime 1/3 - 1/2 cup simple syrup 8 cups water
A note on working with prickly pears: even with mayor visible thorns removed, prickly pears may still have nearly invisible thorns attached. It is best to hold them from the top and the bottom, where thorns are not usually present.
Peel the prickly pears, place in a blender and puree until very smooth. The puree may be passed through a large sieve strainer to remove the seeds. Add the juice of one lime, 8 cups water, and sweeten to taste, keeping in mind that they are naturally very sweet.