Blender to a smooth mix in a blender with basil leaves, lime juice and water. Add sugar. natural sweetener if required,
Chill and serve.
In case you do not have basil or want to add it, skip it or replace with Mint leaves, thyme leaves. But so not keep it overnight it can become bitter due to mint leave. Also do not add much of mint leaves , 4-5 are good.
In place of melons, add any other fruit of your choice that goes well the basil flavour.