Use of reclaimed water is optimized by the decentralized location of Los Angeles' Tillman plant. Photos: Metcalf & Eddy
A Chinese proverb advises, “When you drink the water, remember the spring.” With an exploding global population placing ever-greater demands on a precious, finite resource, that maxim takes on a new urgency.
There will never be more water on Earth than there is today. That fact, combined with several other hard truths, could result in global water shortages within decades. In fact, unless something substantive is done, current water usage rates practically ensure that this will be a very thirsty planet fairly soon. Consider this:Two out of every three people in the world will face water shortages by 2025.Water consumption rose sixfold between 1900 and 1995—more than twice the rate of population growth.More than 1 billion people have no access to clean water, and 3.4 million people die every year from diseases that easily could be prevented through better water supplies and sanitation.At current usage rates, Delhi, India, will run out of groundwater by 2015.
According to a report in the magazine Americas, “The [water shortage] issue can be boiled down to a basic, irrefutable fact: Fresh water suitable for human use is a finite resource, accounting for less than 3% of the earth's total water supply. Of that tiny amount, most—2%— is locked away in ice caps and glaciers, while groundwater adds up to just 0.62%, lakes 0.009%, and rivers a mere 0.00001%. What's more, rapid population growth and associated environmental degradation are contributing to a growing crisis of water scarcity around the world that may reach crisis proportions in a matter of years.”
According to hydrologist Peter Gleik, director of Pacific Institute for Studies in Development, “For nearly 3 billion people, access to a sanitation system comparable to that of ancient Rome would be a significant improvement in their quality of life.”
And the problem is only expected to worsen. At the beginning of the 20th century, 1.65 billion people lived on Earth. By 2050 that number will approach 9 billion people, the United Nations predicts. Since the annual supply of renewable fresh water remains relatively constant, the amount of water available per person will continue to decrease substantially.
Many incorrectly believe this is a Third World problem. However, water sources nationwide already are showing strain. Burgeoning cities throughout the Southwest and West—Los Angeles, San Diego, Phoenix, and Las Vegas—have suffered repeated droughts and have stretched their water supplies to capacity and beyond. But what action is appropriate to prevent a world water crisis?
“Water reclamation and reuse provide a unique and viable opportunity to augment traditional water supplies,” said Takashi Asano, professor emeritus in the department of civil and environmental engineering at the University of California, Davis (UC Davis). “As an important, multidisciplinary element of water resources development and management, water reuse can help to close the loop between water supply and wastewater disposal.”
George Tchobanoglous, professor emeritus of civil and environmental engineering at UC Davis, agrees. “There are a number of new technologies out there—new membrane designs, advanced oxidation, [other ways to mitigate] endocrine disruptors—that are altering the way that we think about things. But the focus must be on reclamation and reuse,” he said.
Asano and Tchobanoglous are not alone in their opinions. “We need to combine the technology, the policy, and the economic power that water has,” said Frank Burton, water expert and independent consulting engineer. “Around the world, development is occurring where there isn't a natural supply of water. To sustain that development and bring peace to these areas of the world, we need a solution. Reclaimed water is that solution.”
But these experts have few illusions about the challenges that impede the use of reclaimed wastewater. Asano noted the significant public perception issues that must be addressed. “For example, what if a schoolyard is watered with reclaimed water? If a child cuts his knee while on that playground, a mother could be very worried that her son will get some kind of infection from whatever she thinks may be in that water,” he said. “Of course, the reality is that that reclaimed water is probably cleaner than her son's drinking water, but the perception is that if it was once wastewater, it's dirty.”