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Faculty Viewpoints

Big Issues: What is Water Worth?

In Yale SOM’s Global Leadership: Big Issues course, Yale experts lead discussions of some of the most significant challenges facing the planet. Julie Zimmerman, a professor of green engineering at the Yale School of Forestry & Environmental Studies, joined the class to explore some of the complex issues surrounding water scarcity and its connection to energy and climate.

  • Julie Zimmerman
    Donna L. Dubinsky Associate Professor of Environmental Engineering; Professor of Green Engineering; Assistant Director for Research at Center for Green Chemistry and Green Engineering

What do we use water for? What is the mandated standard? For short term survival, the global agreement at the UN right now is 20 liters per person per day. That’s the minimum amount of clean water. If you look at the sustainable development goals and the ones around drinking water, that’s what they’re saying. Every person should be afforded 20 liters per person per day.

If you go back and you look at the UN sustainable development goals, the number of people with access to clean water has doubled in the last 20 years. So that’s people who will now have 20 liters per person per day, but there’s still over a billion people who don’t have access to safe water. So it’s about 20% of the population. And interestingly, the UN is now estimating that by 2025, 75% of the world’s population won’t have reliable, clean water.

This is a really interesting debate that continues to rage. It’s been slowly, I would say emerging, but is becoming more and more prominent. This idea of whether water is a public good or a private good, and so there is the debate that water should not be privatized, commodified, traded or exported in bulk for commercial purposes: it is a public good.

And the other side of this said, water and food are basic rights, we pay for food, why should we not pay for water? It’s really interesting and that is where the model’s evolving to is these public-private partnerships. It becomes interesting because you need good government oversight and regulation and then the pricing structure becomes really important.


Just like you talk about embedded carbon in products, we talk about embedded water. Just like you do a carbon footprint, you can talk about a water footprint of a product. How much volume of fresh water is used to produce that product over the production chain? Whether I’m growing crops and I’m harvesting them like cotton and I’m processing them, how much irrigation water goes into that crop? If I’m mining, how much water am I using in that process? Like using cyanide to get gold and how much water am I consuming in that? Or energy production, how much water am I using in fracking and how do I account for that water across the entire supply chain?

And then you can also ask questions about where that water’s coming from. Because we know the geographical distribution of supply chain, I can say that’s coming from a scarce basin or not. We know there’s water dependency. Most countries in the EU, North Africa, and the Middle East are dependent on water resources in other parts of the world. So just like oil is found in the Middle East, you can start asking about which countries are water rich and are really good at exploiting that resource and selling it to the rest of the world.

And then you can start to ask questions about from a global perspective, is virtual water trade a mechanism to increase global water efficiency? What’s the risk of shifting our environmental impacts from producing in our own country to somewhere else? And then from a national perspective, not my academic environmental perspective, is this a solution for me as a water-scarce country and what is the risk of becoming water dependent? Of saying, “For my water resource benefit I’m going to import those crops, that food, those products from somewhere else,” and am I setting myself up for an alliance relationship where I’m at a disadvantage because I need food to feed my people and I have now said I can’t grow it or it doesn’t make sense for me to grow it in country. I’m going to import those goods.


California, two years before the drought, set audacious carbon goals that they were going to reduce carbon emissions from the state of California and they spent tens of millions, hundreds of millions of dollars upgrading the energy grid. So California’s energy efficiency programs, here’s what they spent; here’s gigawatts of energy they were able to save off the grid. Here’s the funding they put in. So, $1.5 billion in 2006 to 2008. Here’s the cost per kilowatt hour that they spent saving those carbon emissions off the grid.

“If I solve my water-use problem, it should also solve my energy problem, which will solve my climate change problem.”

We went in and said, “If you had tried to address your carbon goals through water conservation instead of through upgrading the grid, going to renewables, building out PV, doing smart metering, just went in and spent money on water conservation, water use efficiency metrics, you would have saved about the same amount that you saved from trying to upgrade the grid. You would have done it at half the price almost and it would have only cost you 12 cents per kilowatt hour instead of 22 cents per kilowatt hour.”

But we don’t think like that, right? The carbon goal has to come from the energy sector. They never ask the people in the Department of Environment, can you realize these carbon goals through water savings? And they spent all that money and if they had done it through water use, they would have saved money and they would have been better positioned for the drought. So we don’t think about this nexus perspective from a government management at all in terms of these resources and we’re often wasting a lot of money because we don’t think about that nexus.

So, if I solve my water use problem, it should also solve my energy problem, which will solve my climate change problem. We need to think about when we’re pursuing these technologies or these management strategies that we are winning and finding synergies.

Department: Faculty Viewpoints