While using water is one interesting point of the actual paper(from which this article is written), I would say, to a lay person, water volume makes more sense

While using water is one interesting point of the actual paper(from which this article is written), I would say, to a lay person, water volume makes more sense than arbitrary values like KiloJoules or KiloWatts, because I can imagine what a 20mL water would look like, but can't imagine what 20mJ or 20mW looks like.