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dam-l Waste water for drinking-LS




>
>WASTE WATER RECLAIMED FOR DRINKING
>
>WASHINGTON, DC, March 12, 1998 (ENS) - How would you like to drink
>reclaimed wastewater? Need, coupled with advances in water treatment
>technology, is motivating a small but growing number of American cities to
>use reclaimed wastewater to supplement drinking-water supplies. But,
>important questions remain regarding the level of treatment, monitoring,
>and testing needed to ensure public safety, a new National Research Council
>(NRC) report concludes.
>
>"Issues in Potable Water Reuse," written by an NRC committee of experts,
>says that reclaimed wastewater can be used to supplement drinking-water
>sources, but only as a last resort and after a thorough health and safety
>evaluation.
>
>The committee reviewed reclaimed-water projects now operating in the United
>States, including those supplying Northern Virginia, Orange County,
>California, and Phoenix, Arizona. It also examined feasibility studies
>conducted by the cities of San Diego and Tampa.
>
>Limited data from projects and studies nationwide show that highly treated
>reclaimed wastewater produced drinking water of excellent quality, and
>that no obvious health effects have been found in animal tests or in
>communities where reclaimed water has been used. These results are
>insufficient, however, and more information is needed, the report says.
>
>Before deciding to add reclaimed wastewater to city water supplies,
>municipalities first must fully assess health impacts from likely
>contaminants and develop comprehensive systems for monitoring, testing, and
>treatment, the report recommended. Other water sources and conservation
>measures also should be tried to the extent practical, before turning to
>reclaimed waste water.
>
>Because regulations for safe drinking water were not developed with
>reclaimed water in mind, they may not be the best standard for testing its
>quality, the committee said. Reclaimed water may contain sources of
>contamination that cannot be determined through current testing or
>treatment processes.
>
>When considering reclaimed wastewater for public water supplies, the
>report distinguishes between direct and indirect use. Adding highly treated
>wastewater directly into a water supply without storing it first in a
>reservoir is not a viable option. Indirect use is viable, however, and that
>approach was examined by the committee.
>
>Indirect use augments the drinking-water supply by adding reclaimed treated
>water first to a lake, reservoir, or underground aquifer. The mixture of
>natural and reclaimed water is then subjected to normal water treatment
>before it is distributed as drinking water for the community. Since the
>1960s, California's Los Angeles County has operated an indirect-use system
>in which wastewater, mixed with storm water and river waters, supplies
>about 16 percent of total flow into ground-water basins. This mixture then
>is used as a source for drinking-water supplies.
>
>Given health and safety concerns, the committee identified key priorities
>for water agencies that add treated wastewater to their systems, or are
>considering doing so:
>
>*  All major sources of household, industrial, and agricultural chemical
>contaminants in reclaimed water should be documented and removed based on
>existing federal clean-water standards. Since it is unclear whether or not
>highly treated wastewater contains harmful levels of byproducts from
>disinfection processes such as chlorination, this issue should be addressed
>by the research community.
>
>*  The Environmental Protection Agency should sponsor a study to develop
>methods for better detection of new pathogens, the National Research
>Council committee report recommends. Most outbreaks of waterborne disease
>in the United States are caused by parasites and viruses, yet few
>drinking-water systems monitor for the full range of such pathogens.
>
>*  After reviewing the few studies that have examined the health
>implications of drinking reclaimed water, the committee said that different
>approaches are needed to test the safety of reclaimed water. Conventional
>toxicology tests developed by the food and drug industries are not
>appropriate for evaluating the risks from complex chemical mixtures that
>can be found in reclaimed water. Alternative studies, such as tests using
>fish in source water, should be undertaken to provide a broader range of
>data about possible harmful effects to living organisms.
>
>*  Research also is needed on the level of viruses and parasites in all
>waters and the effectiveness of both conventional and advanced water
>treatment processes in removing these pathogens. The federal government
>should undertake population studies that compare the disease rates over
>time among individuals exposed to reclaimed water to the disease rates
>among individuals who use a different water source.
>
>*  There are two essential keys to the safe, reliable operation of a
>reclaimed-water treatment system: good design that provides redundant
>safety measures to prevent contamination, and monitoring systems that
>detect variations in water quality and system performance. Other measures
>should be implemented as well. Since waterborne viruses, bacteria, and
>parasites pose the greatest threat to public safety, water treatment
>procedures for removing them should necessarily be the most stringent.
>
>Communities using reclaimed water should implement well-coordinated, public
>health surveillance systems to document and provide early warning of any
>adverse health effects associated with the ingestion of reclaimed water.
>
>The study was funded by the American Waterworks Association Research
>Foundation, the County Sanitation Districts of Los Angeles County, the Phoenix
>Water Services Department, the U.S. Bureau of Reclamation, the Environmental
>Protection Agency, the Water Environment Research Foundation, and the
>National Water Research Institute. The National Research Council is the
>principal
>operating agency of the National Academy of Sciences and the National
>Academy of Engineering. It is a private, non-profit institution that provides
>science advice under a congressional charter.
>
>Copies of "Issues in Potable Reuse: The Viability of Augmenting
>Drinking-Water Supplies with Reclaimed Water" will be available in April
>from the National Academy Press; Tel: 202-334-3313 or 1-800-624-6242.
>
>---
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>

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      Lori Pottinger, Director, Southern Africa Program,
           International Rivers Network
              1847 Berkeley Way, Berkeley, California 94703, USA
                  Tel. (510) 848 1155   Fax (510) 848 1008
                        http://www.irn.org
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