Wash the jaguas, then cut into small pieces. Place in a container with a lid with a capacity of 2.5 liters (1 gallon). Add the water. Cover with a piece of cloth or a clean kitchen towel (no lid).
Leave it on the kitchen counter for 24 hours, in a place where it's not cold, and there isn't too much light.
After 24 hours have passed, remove the cloth, and close with the lid. Move to the fridge for the next 4 days. By then tiny bubbles should have formed in the liquid.
Strain and add sugar to taste. Serve with ice.
You can reuse the jagua by refilling again and letting it rest in the fridge for 5 more days. It's good just for one more time, after that, throw them away.