Friday, February 26, 2010

What is your Water Footprint?

Carbon footprint is a major topic of discussion these days and every one seems to have an opinion on it, one way or the other. While that debate goes on, I would like to introduce you to the concept of Water Footprint. Have you thought about it?

Several items play into creating our Water Footprint: the water that is consumed by us, the water that is used to create and dispose the products we use, and the global trade of these products. The total Water Footprint can be broken down into three major components: the blue, the green, and the grey. Blue water footprint is the volume of freshwater used up from the global water resources to produce the goods and services consumed by the individual or community. For example, the use of water to irrigate crops. Green water footprint is the volume of water used up from the global green water resources such as the rainwater stored in the soil as soil moisture. And, grey water footprint is the volume of  wastewater generated from goods and services used and is calculated as the volume of water required to dilute the wastewater to attain a quality better than or equal to international water quality standards. The graphic below shows your total water footprint.

Slide 6 -->
Source: Hoekstra,  A.Y. (2008) Water neutral: reducing and offsetting the impacts of water footprints, Value of Water Research Report Series No.28, UNESCO-IHE.

Historically, we have been aware of only the little box on the left named "water withdrawal" because that is what we see as the gallons of water consumed on our water bills. But we fail comprehend the amount of water we consume on a daily basis via the products and services we use.

Here is your water cost for common items used daily:
A cotton shirt = 2,700 litres (713 gallons)
A cup of coffee = 140 liters (37 gallons)
100 gms (~3.5oz) of chocolate = 2,400 liters (634 gallons)
1 kg (~1/2 lb) sugar = 1,500 liters (396 gallons)
1 kg (~1/2 lb) tomatoes = 180 liters (48 gallons)
1 glass of wine = 120 liters (32 gallons)
1 hamburger = 2,400 liters (634 gallons)
1 kg leather (as in shoes, bags, etc) = 16,600 liters (4,385 gallons)
1 sheet of A4 paper = 10 liters (2.7 gallons)

And yes, the 'green fuels' like bio-ethanol and bio-diesel have water footprints too. This footprint does not get incorporated into the case for "green" energy, but they should!! See the figure below.

Slide 27
Source: Gerbens-Leenes, W., Hoekstra, A.Y. and Van der Meer, T.H. (2009) The water footprint of bio-energy, Proceedings of the National Academy of Sciences, PNAS Early Edition, doi:10.1073/pnas.0812619106.

Next, there is a global perspective to water footprint since global trade influences the water footprint to a great extent. Consumption of goods in one place has significant impact on the water resources in another place – and that is nothing new.

Here is a comparison of the countries with their water footprints – no surprises, really!

Slide 33
[Hoekstra & Chapagain, 2008]

I am not against global trade, but buying local would be a good practice. It's hard, I know!
I don’t want you to get all guilty and stop drinking water and eating, but being conscious of your impact in this world is a good thing to be aware of. You can buy your way out of your carbon footprint and feel all giddy about it, but the only way to offset you water footprint is to be aware of the choices you make.

To the "Green Community", I urge you to start including water footprint in your calculation. A design / plan can only be truly sustainable if "WATER" is considered along with energy.

To all you tech savvy people out there who care about your water footprint, there is an iPhone App for you!!

Credit: Thoughts and information presented in this blog is from It is an amazing website with loads of information. I urge you all to visit this website and learn more about Water Footprint.

No comments:

Post a Comment