Water, water everywhere?

Posted by Dan Karney on Oct 14, 2011

Filed Under (Environmental Policy)

This week I came across an interesting website called The World’s Water from the Pacific Institute that collects data about freshwater supply and usage by country.  I already knew that the United States consumes a lot of water, but I want to use this website to compare quantitatively how much water the U.S. used relative to rest of the world.  Not surprisingly, the data reveal that on a per capita basis, the U.S. consumes the most freshwater of all countries with large water supplies.  Furthermore, if all countries had the water consumption rate of the U.S., then total worldwide freshwater withdrawals would become nearly three times greater.

To begin my analysis, I note three interesting facts about U.S. freshwater supplies and consumption, using data from the website cited above.  First, the U.S. ranks 4th in annual renewable freshwater resources with 3,069.0 km^3/yr, and ranks ahead of Indonesia but behind Canada.  Brazil ranks first in freshwater resources with more than 2.5 times as much as the United States.  Obviously, larger countries in land-mass have an advantage in this ranking, since more area provides more opportunity for freshwater resources, all else equal.

Second, the U.S. ranks 9th in annual freshwater withdrawal per capita, and ranks ahead of Suriname but behind Tajikistan.  Interestingly, the countries that surround the U.S. in this ranking are not similar to those countries in the previous ranking, with the exception of Canada that occupies the slot three places below the United States.  In particular, the countries near the top of the consumption per capita list are generally low on ranking of total freshwater supply, meaning that countries with large supplies like Brazil can be low on the consumption ranking (where Brazil is 87th ranked).

Third, the U.S. uses 1600 cubic meters per person per year (m^3/p/yr) of freshwater.  In comparison, China only withdrawals 550 m^3/p/yr of freshwater, almost 3 times less (where China is 71st ranked).  Thus, the U.S. not only has a high ranking in withdrawals per capita, but has significantly larger withdrawals.

Finally, I apply the per capita withdrawal rate in U.S. to all countries and find that the worldwide total withdrawal would almost triple compared to current levels.  Of course, increasing the quantity supplied of freshwater comes at a higher cost.  Therefore, as the demand for freshwater increases as worldwide GDP levels increase, then the amount of money spent freshwater consumption will increase dramatically!