Future Demand for Water


Future Demand for Water

What will the future bring?

What will the future bring? Good question, right? How can we gauge what water demand and availability will be in the future, particularly with projected large increases in population and potential climate change superimposed? Not to alarm you, but to inform you, we will go through the exercise of making such projections, both for the U.S. and, on a more limited basis, for the world. What do we need to know for making such estimates? First, let's jot down some ideas. Then we will continue the process below.

Food for Thought

1. What do you think we would need to know in order to predict future demand for water? Take a minute to jot down what you think one would need to take the first crack at this.

Click for answer...

ANSWER: Answers will vary. Clearly, we will need to know something about population growth and climate.

First, here is an expert opinion as to how the future will go…

In Human Population and the Environmental Crisis Ben Zuckerman and David Jefferson write: “At a low population density, a society may be able to derive its water from rivers, natural lakes, or from the sustainable use of groundwater. As the population grows, so does the volume of water needed (we will assume demand is proportional to population size). Moreover, levels of waste discharge into the environment will grow as the population rises. Thus, the available unmanaged supplies deteriorate at the same time that demand on them is increasing…A destructive synergy is at work: population size affects the water resource in a manner that is not one of simple proportionality.”

What was it Yogi Berra (N.Y. Yankees catcher and later Manager) infamously said…"It's tough to make predictions, especially about the future." Well, that is a truism, but let's see what projections are being made regarding future population growth, because, clearly, that's one of the inputs we need to determine potential future water use globally. The present global population (as of 2014) is approximately 7.25 billion people. Interestingly, the top three countries, in terms of population, are China, India, and, yes, the United States, in that order (Figure 17). But, by 2050 the global population is estimated to be 9.6 billion people by the United Nations—a staggering 33% increase in the next, say, 35 years! So, at the minimum, if we assume that water use will increase linearly on a per person basis, we would expect that this rate of growth will require 33% more fresh water by 2050. Is that a problem? Do we have excess capacity to supply this water?