This is a recipe I adapted to use up more basil and also some of the lovely cucumbers that come in the CSA box during the summer. You can use lemons or limes and basil, mint, or any other herb you think will work.
Cucumber Agua Fresca
2-3 large cucumbers, peeled and seeded
Juice of 3-4 lemons and or limes
2 sprigs of fresh basil
1/4 C sugar or to taste
Blend together until smooth. Add 3 cups of water, and chill for several hours or overnight. Strain and serve.