Noting that desalination of seawater and brackish water "adds several dimensions of complexity beyond what is typically involved in the production of drinking water," the World Health Organization has released draft guidance on the health and environmental aspects of desalination.
WHO seeks comment by October 31 on the draft of "Desalination for Safe Water Supply" and expects to publish a final version in English by year's end. An Arabic translation will also be prepared using funding provided by the Kuwait Foundation for the Advancement of Science.
WHO noted that desalination technologies are improving and growing rapidly worldwide and have "significantly broadened the opportunities to access major quantities of safe water in many parts of the world." Since desalination was introduced about 50 years ago, more than 12,000 desalination plants have gone into operation, producing about 40 million cubic meters of water per day, despite the high cost of the technology, according to the report.
"Costs are still significant but there has been a reducing cost trend, and the option is much more widely available," the report says.
While WHO Guidelines for Drinking-Water Quality cover a broad spectrum of contaminants, the 2000 Berlin Coordinating Committee meeting requested additional guidance in the area of desalination because it uses nontypical source waters technologies, which might not be adequately addressed by existing WHO guidelines.
Of particular concern is the presence of microbes from coastal and marine sources and chemicals in source water or that are not well removed by the desalination process.
The monograph is divided into five segments: technology, health, marine and sanitary microbiology, monitoring and environmental impact assessment. Each section was produced by an international committee of experts and concludes with recommended guidance. Some also identify research issues.
Please visit http://www.who.int/water_sanitation_health/gdwqrevision/desalination/en/  for more information.