If you want to double the recipe and you have a big blender, great! If you have a little one like mine, just do it in two batches.
Strain the blended fruit and water through a fine mesh strainer to remove any big parts and excess seeds. My extractor-type blender pulverized most of it, so very little stayed in the strainer. If you have an even fancier one, you may decide to skip this step.
Mix well and check the consistency until you have one that makes you happy. I'm going to leave it a little thick so I can add cold fizzy water when I'm ready to drink it.