In a blender, add 1 cucumber and 1 cup of water. Blend until smooth.
Strain mixture through a strainer into a bowl then transfer to a pitcher. Discard the solids.
Repeat the process with the remaining cucumbers.
Add the sugar and mix well. If using lime juice, add it at this point and adjust sugar to taste.
Cover and refrigirate for at least an hour.
Serve over ice.
