I don’t know about you but I find it a challenge to calculate my water footprint. There is a global non-profit (waterfootprint.org) that is willing to help with that and when I did some rough calculations the result was that I use 5,000 litres of water per day! This can’t be right. I shower for less than five minutes, we don’t water our lawn or wash our vehicles, we have a rain barrel etc. So what am I doing that induces such a high volume? As someone in the economic middle class, I have the ability to purchase most commercial products and consume a wide plethora of foods, all of which require water (and in most cases this water is being drawn from the municipal system that has gone through a treatment process).
I decided to calculate my water footprint again and base it on a simple Parisian lunch, just for fun. One baguette – 155 litres of water, the cheese was a bit trickier to figure out but a 250 gram block uses about 800 litres of water, and now for the wine – this used the least amount per portion size at only 109 litres per glass, albeit a small glass. My simple lunch now weighs in at over 1,000 litres of water. With an average of 30 lunches per month, I start to see how my water footprint could be over 5,000 litres per day. It is eye opening to reflect upon the volume of water not only my lunch requires but all of the products I consume – from my shoes and clothes to the phones and computers I use for work and play.
The water footprint is starting to become a common household term, which stems from what industry experts used to refer to as virtual water. The concept of water footprint was first introduced in 2003 and serves to link our personal consumption levels with the global use of fresh water. What is different about the calculation of the water footprint as compared to calculating virtual water is the break down of where the water originates; a blue water footprint is in reference to the surface and groundwater that has been utilized, the green water footprint refers to the volume of rainwater consumed while the grey water footprint indicates the volume of water needed in order to “assimilate the load of pollutants based on existing ambient water quality standards” (Mekonnen and Hoekstra 2011). This last measure is relatively new yet important to the overall picture of how water is consumed globally.
With all these factors in mind, I start to have a clearer picture of how my perceived lean water ways are not as they meet the eye. Interested in your own water footprint? Check out: www.waterfootprint.org for more information!
Questions or comments for Sonya? Send an email to: firstname.lastname@example.org / waterwoman.ca
M.M. Mekonnen and A.Y. Hoekstra (May 25, 2011) The green, blue and grey water footprint of crops and derived crop products. Published in Hydrology and Earth System Sciences, Issue 15, University of Twente, Enschede, The Netherlands.