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World Water Day 2013: What is Your Water Footprint?

To mark World Water Day at Aquatic Informatics we watched the movie ‘Last Call at the Oasis’. In discussion about the issues raised by this movie one of our senior developers expressed surprise at the magnitude of the water footprint for everyday products.

For example, the water footprint for a t-shirt was given as 700 gallons!

I don’t know whether the notion of accounting for your water footprint will catch on or not. A few years ago the idea of calculating your carbon footprint got quite a bit of press and even though carbon calculators have never caught on the notion that your carbon footprint matters seemed to stick. Equating energy use with a carbon footprint is intuitive – if I turn on a light my footprint grows whereas if I walk to work my footprint shrinks.

Water is a bit more complicated – for starters you need to consider the distinctions between Green water, Blue water and Grey Water. Green water is the volume of rainwater evaporated. Blue water is the volume of surface or groundwater evaporated and Grey water is the volume of water polluted. If you total up the evaporative losses from cotton fields with the grey water effluent of cotton mills you wind up with 10,000 litres of water used for every kilogram of cotton produced.

It is difficult and possibly impossible to accurately estimate the fate of evaporated water.

In some cases, the evaporation from irrigated farmland is recycled in convective storms within the same watershed. In other cases, the evaporated water is transported downwind in a form of massive inter-basin transfer (or perhaps exported offshore). Even if recycled within the same basin future beneficial uses of the water are impacted by the increased unpredictability of water availability.

Losses of water to the atmosphere are really a re-distribution of water. The point being that we don’t know where or when that water will be available for use again.  Grey water is a more persistent and troubling issue. I think the Grey water component is a greater motivator for change.

The presentation of factoids such as that a hamburger has a water footprint large enough to fill a swimming pool does not reduce my appetite for hamburgers.

However, if I knew more about the nutrients, pathogens, pesticides and pharmaceuticals released into natural streams as a direct result of my hamburger then I think that might motivate me to choose a veggie burger.

The water footprint concept is interesting but it remains to be seen if it will be useful.

It is interesting to declare that it takes 1500 litres of water to produce 1 kg of sugar, but will that information result in a change in my behavior in the absence of information about less consumptive alternatives?  The water footprint campaign needs to move past the shock and awe phase and become framed in terms of helpful information to guide water smart choices.

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  • Michael Lathuilliere
    Posted at 2:36 pm, March 22, 2013

    Hello Stuart,

    I think it’s great of Aquatic Informatics to start questioning water footprints (WF). This is definitely an important indicator. Last year, the focus of Canada’s World Water Week was the WF, a necessary step in propagating knowledge about this relatively new metric.

    I’d like to add a few things to your comments on the WF as someone intimately involved with it, especially the green water portion. You’ll see that the work behind this indicator goes beyond the accounting steps. Important considerations are the water source, the WF sustainability assessment and WF use in life cycle assessments.

    The motivation behind the separation of water into blue and green components was to shift our thinking about water resources, especially the source. Most water resource management revolves around surface water and groundwater (forgotten oftentimes), both of which are blue. New water management strategies can arise if you consider the water source to be precipitation, which subsequently separates into blue and green water at the soil. Soil water had to be accounted for particularly in the case of rainfed agriculture since most crops are rainfed on the global scale. Gray water was introduced later by the WF Network and remains contested at this point since it is expressed as a volume and is particular to the pollutant of interest.

    WF, as defined by the WF Network, is not an impact indicator but a resource use indicator. You’re right: knowing that it takes 1000L of water per liter of milk doesn’t mean anything without context. This is why the WF Network has introduced a sustainability assessment to inform water resource management within the confines of a watershed.

    WF impacts can be expressed in a life cycle assessment (or LCA), a systematic and science based method which evaluates environmental impacts (but also social and economic) at all life cycle stages of a product or service: resource extraction, processing, packaging, transport, use, all the way to disposal/reuse/recycle. At this point, the framework for WF in LCA is based on competitive uses (human vs. environment). What is exciting is that LCA considers more than just water, it includes greenhouse gas emissions (carbon footprint), land use, contaminant use, etc. with impact pathways such as eutrophication, acidification, ozone depletion to estimate “end point” impacts on human health, environmental quality, resources and ecosystem services. It is a holistic approach that can truly enlighten decision-making. There is currently an ISO standard in the making for water footprint within this LCA context to formalize the approach (ISO 14046), due in a couple of years.

    WF, just like the carbon footprint are definitely “in”. The Carbon Disclosure Project (or CDP) is actively involved in setting the reporting requirements for hundreds of companies. The CEO Water Mandate and the Sustainability Consortium regroup many organizations and corporations who have made the pledge to reduce their water footprint (from beer to apparel) and advance research in reducing impacts all along the supply chain. On the one hand, companies realize that they need strong metrics to inform their corporate sustainability strategies and identify the most effective way to reduce their impacts within the boundaries of their business and through their supply chain. On the other, investors and consumers are increasingly asking for this information: environmental labeling is making its way to Europe and many companies are already reporting their carbon footprint (soon WF?) just like they are reporting their financial results.

    Happy World Water Day 2013!

    All the best!

    By Michael Lathuilliere

  • Shwetha Karthik
    Posted at 12:50 pm, March 26, 2013

    Every day must be water day and one must think saving water and minimum usage of water, and minimizing wasting water, one simple suggestion is, in homes we can put a filter like sprinclers with small holes to all the taps, especially near kitchen washbasin tap, we can save max amount of wastage of water.

  • Ibiyemi Olu-Daniels
    Posted at 12:51 pm, March 26, 2013

    Importance of freshwater and sustainable management of freshwater resources

  • Anita Mukherjee
    Posted at 12:51 pm, March 26, 2013

    “water water every where but not a drop of water to drink ” this line is known to every one . So i suggest water for drink or” low cost safe drinking water to every one” and this mission should be every one . we should not waste water or drinking water .

  • B.S.Thandaveswara Basavapatna
    Posted at 12:52 pm, March 26, 2013

    The next world war is for the drinking water.
    The governments are not bothering about this major issue. Every citizen,human beings animals have the right access their requirement of daily reduce wastage.conserve water. water politics is klling the people

  • Anita Mukherjee
    Posted at 12:53 pm, March 26, 2013

    A Man or Animal can live with out food a day or two but not with out water 24 hours . So our mission should be in one line and its obey to all , that is ” We do not Waste a Drop of Water in any Time This should be the Slogan for all and also through the School Children , College , University and all the Govt offices where most of the water Taps are very poor due to non maintenance . The day will come we have procure our drinking water from the waste water , then we will realise the truth . The Road side water Taps should close down immediately , from this source of water we could Reserve our safe water for the future , but the Govt will not listen to me or us as because their VOTE BANK is there .

  • Anita Mukherjee
    Posted at 12:53 pm, March 26, 2013

    My mission is water and safe drinking water for all . Thus Every Mother and also the other members of the family should alert and not to waste water and Teach their little children from home .

  • Dianne Wells
    Posted at 2:01 pm, March 27, 2013

    With 1% of the world’s fresh water available to the entire population, the decision to manage water use is no longer a choice, but a way of life. As I traverse the length and breadth of Trinidad and Tobago teaching communities of the benefits of Rainwater harvesting, these initiatives go beyond harvesting rainwater to becoming watchdogs of the environment, starting at the primary school levels all the way to responsible corporate partners.

    Culture change in the way we use water is a critical component moving forward. Chlorinated water is not necessary for many of our household practices and it is now necessary to educate our population on the benefits of using recycled water and implementing waste water treatment plants for industrial use etc.

  • Michael Lathuilliere
    Posted at 1:48 pm, April 2, 2013

    Hello Stuart,

    The thinking about the WF of fish is interesting and I haven’t seen any studies on that yet. Possibly because the WF is a representation of human appropriation of freshwater use and pollution. In that case, how to account for the several years of a wild salmon living in the ocean? If the salmon were farmed you could figure out the volume required and polluted per tonne of salmon produced, in which case you are closer to the hamburger example.

    The WF sustainability assessment is the third and final step for determining sustainable water use as defined by the WF Network after (1) definition of purpose and scope and (2) WF inventory. The sustainability assessment compares the human activity expressed in the WF to local availability (e.g. streamflow) defined in space and time at the source of interest. These sources could be local in the case of a brewery taking water from a nearby river, or distant in the case of an irrigated wheat field in Sask. (considered a virtual water import for the brewery).

    I recommend a global water sustainability assessment by Hoekstra and Mekonnen (2012) that does this type of assessment explicitly. You’ll see that the WF in the Australian Murray Darling basin is larger than streamflow in the summer months because the study allocates a percentage of streamflow to ecosystem services which rely on water. In WF jargon, this difference is called blue water scarcity. Important: the sustainability assessment is not an impact analysis, meaning that the findings are not meant to quantify whether a wild salmon will make it up the river. It is meant to highlight water use within the context of availability either geographically or for a process. Impacts of WF are better defined in a life cycle assessment, which is not what the WF Network uses at this time but which should be explicit in the ISO 14046 standard when it becomes available.

    Some countries in Europe are looking to adopt policies focusing on the WF, Spain and Holland in particular. A UBC study by Brown et al (2009) looks at the agricultural WF of 2 BC watersheds. One conclusion that struck me was that the most water intensive product in the Okanagan was also the crop with the lowest value, namely alfalfa. This also raises questions about agricultural policies and their role in affecting WF without even considering water use. Other policies such as groundwater regulation in BC, I think, would also have impacts on reducing WF of crops (demand side management through pricing for example).

    All the best,

    Brown, S., Schreier, H., Lavkulich, L.M. (2009) Incorporating virtual water into water management: A British Columbia example. Water Resource Management. Vol 23. DOI 10.1007/s11269-009-9403- 8. pp. 2681 – 2696.

    Hoekstra, A.Y. and Mekonnen, M.M. (2012). The water footprint of humanity, PNAS 109(9) 3232-3237

  • Frederick Ross
    Posted at 1:50 pm, April 2, 2013

    In the water demand or footprint did we account for the natural nitrogen fertilizer value added by Alfalfa?

    Or the rotation required for crops to remain pest free (chemical avoidance). What about the water demand for milk or beef which uses huge amounts of alfalfa? Is the water double counted?

  • Michael Lathuilliere
    Posted at 1:50 pm, April 2, 2013


    I just realized that my previous comment had an error, it was hay/fodder not alfalfa which had the highest WF. See results here:

    The study focused on water use not on other resources such as fertilizer or benefits from N fixation. Since the study was published in 2009, I am guessing that the work took place just as the gray WF was being introduced by the WF Network (~2007-08). This inclusion would have likely increased the WF of crops/livestock by considering NPK fertilizer application (see the study by Hoekstra and Mekonnen in the previous post). The gray WF represents the amount of water required to assimilate a pollution load to acceptable levels of pollution. This concept is still contested by experts and the debate is ongoing on how to link pollution and water volumes.

    Livestock and milk are typical examples where you have to apply life cycle thinking to determine the WF of a product. The livestock portion of the study uses the WF of feed (local alfalfa/hay or imported grain), it includes water used to mix the feed, drinking water consumed by the animal, animal life expectancy before calculating a WF in m3/ton based on the animal product output which can be meat or dairy.

    You highlight a very important point though: there might be hidden benefits that will be missed if only one indicator is used for decision making. This is why current studies have included multiple indicators for resource use, such as the “Footprint Family” of water, carbon and ecological footprints.

    For impact assessment of production and consumption, I’ll mention again life cycle assessment which provides a holistic view of a process and can really help pick the better of the good decisions regarding impacts. Most people I ask will answer that the largest impact of a bottle of soda occurs at the disposal stage of the plastic bottle, but one study showed that it was actually the refrigeration process which had the largest impact (you can imagine this from the energy production of coal plants in the US). So which policy would have the largest impact for the producer? Of course, recycling is good and should not be forgotten, but in terms of this company’s sustainability strategy, the investment in energy efficient fridges would be the better of the good solutions (and the benefits can be calculated as well).


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