I recently received a newsletter that talked about something that has bothered me from time to time. I cant tell you how often I hear knowledgeable people, environmentalists and journalists usually, say that were running out of water. Were not running out of water. We cant run out of water. For all intents and purposes, we have a constant amount of water on this planet; we cant destroy water or make new water (at least in amounts that would make any kind of difference). The hydrologic cycle is a closed loop. Its one of the primary differences between the energy crisis and the water crisis; when we use oil or coal or natural gas, we really do use it up, ultimately converting it to carbon dioxide and water, and we really are running out of fossil fuels.

(Just occurred to me: I wonder if anyone has calculated how much water has been added to the hydrologic cycle by fossil fuel burning?)

I suspect the majority of people who talk about the world running out of water do realize that we aren’t truly running out of water. And there is a water crisis in many parts of the world. But it’s not because we are losing water, but we are either contaminating it and making it less potable, or moving it away from where we need it to a less convenient place (like the oceans). There are several ways in which we’re moving potable water away from where we need it. One is pumping aquifers beyond their sustainable limits, i.e., removing groundwater faster than it can be recharged. Another way is the creation of reservoirs by dams, especially is hot dry regions. The amount of water that evaporates from reservoirs can be staggering. As few years back at the Geological Society of America national meeting, Todd Halihan from Oklahoma State University estimated that 700 billion liters of water are evaporated from man-made lakes in Oklahoma annually, enough water to supply 20 million people. That evaporated water isn’t lost of course, but enters the atmosphere. Some of it stays in Oklahoma as rainfall, but a lot of it is transported away and rains elsewhere.

Here’s another thing that bugs me, something I heard Charles Fishman, the author of “The Big Thirst: The Secret Life and Turbulent Future of Water,” say during a radio interview. He contrasted the amount of water the average American uses daily for household (99 gallons; we’re in the top 10) with the amount of water used for electricity generation (250 gallons per person), which works out to each of us using “10 gallons of water an hour every hour of every day just to power our computers and our refrigerators and our washing machines at home.” While I don’t doubt those numbers, those numbers are misleading. Almost all of that water is used for cooling, and is not consumed but returned to the water body from which it was taken for later re-use. In Illinois, about 90% of water withdrawals go to thermoelectric power generation.

The authors of the newsletter suggest instead of talking about consumptive use of water from a quantity standpoint, we should consider it more from a quality standpoint. Here’s what they recommend: “Consumptive Water Use: Water removed from available supplies that is either not returned to a water resources system or returned in a degraded condition.” This seems like a much more sensible approach to me.