When most of us turn on the tap, we find clean, flowing water. In fact, we’ve come to expect that across this country, and the alternative is both annoying and newsworthy.
But water resource experts – know as hydrologists – are increasingly concerned about the long-term availability of drinking water worldwide. The problem isn’t that water is scarce. But, when we look at the world’s water, and discount salt water, frozen water, and water in the deep Earth – only a scant three-tenths of one percent of the water is of high quality to humans.
Hydrologists warn that we must make better use and reuse of water if we are to continue to supply the world’s rising population and the crops that feed us.
The most obvious sources of water are nicknamed blue water, which is found in lakes, rivers, reservoirs, and groundwater. It is generally of high quality. Gray water is water that has been previously used in households and industry. Gray water may contain some impurities, but it can often substitute for blue water for waste disposal and landscape watering. We shouldn’t simply dispose of gray water in local blue-water reservoirs.
Green water is water that is accessible in the soil for plant use. Because plant roots discriminate against many contaminants, gray water, if it’s not too saline, could supplement natural sources of green water, for instance to enhance irrigation waters for crops. Right now, a large fraction of the Earth’s blue water is used for irrigation, when gray water would do just fine.
**********
.
Web Links
Photo, taken on September 20, 2009, courtesy of Smitha Murthy via Flickr.
Earth Wise is a production of WAMC Northeast Public Radio. Support for Earth Wise comes from the Cary Institute of Ecosystem Studies in Millbrook, NY.