And now to confuse you! How is the public expected to understand water footprinting metrics?

Abstract

It takes 140 litres of water to make one cup of coffee [1]. Or is it 80 litres [1]? Or maybe even 208 litres of water per cup [2]? Or 130 litres [3]? These are all different numbers for what seems to be for the same thing. Even a scientist that understands these numbers might be confused as to why they are different, so how do we expect a nonexpert to be able to make realistic sense of water footprint numbers, with the same being true for carbon footprinting or other life-cycle assessment type studies.Water footprint metrics report blue-, green- and grey water but rarely split them into their component parts when reported in mass media. Even if reports included individual components, would the public understand what these meant? This work looks at how water footprinting is reported and why there might be differences as seen in the numbers above. Do the values reported give the public a realistic description of how much water is actually used, or does the media simply use footprinting numbers as a shock tactic for increased readership? This paper gives a short description of the water footprint, followed by a discussion on where and how differences in water footprinting numbers might originate.