WASHINGTON — With recent advances in
technology and design, treating municipal wastewater and reusing it for drinking
water, irrigation, industry, and other applications could significantly increase
the nation''s total available water resources, particularly in coastal areas
facing water shortages, says a new report from the National Research Council.
It adds that the reuse of treated wastewater, also known as reclaimed water, to
augment drinking water supplies has significant potential for helping meet
future needs. Moreover, new analyses suggest that the possible health risks of
exposure to chemical contaminants and disease-causing microbes from wastewater
reuse do not exceed, and in some cases may be significantly lower than, the
risks of existing water supplies.
"Wastewater reuse is poised to become
a legitimate part of the nation''s water supply portfolio given recent
improvements to treatment processes," said R. Rhodes Trussell, chair of the
committee that wrote the report and president of Trussell Technologies,
Pasadena, Calif. "Although reuse is not a panacea, wastewater discharged to the
environment is of such quantity that it could measurably complement water from
other sources and management strategies."
The report examines a wide range of
reuse applications, including potable water, non-potable urban and industrial
uses, irrigation, groundwater recharge, and ecological enhancement. The
committee found that many communities have already implemented water reuse
projects -- such as irrigating golf courses and parks or providing industrial
cooling water in locations near wastewater reclamation plants -- that are
well-established and generally accepted. Potable water reuse projects account
for only a small fraction of the volume of water currently being reused.
However, many drinking water treatment plants draw water from a source that
contains wastewater discharged by a community located upstream; this practice is
not officially acknowledged as potable reuse.
The report outlines wastewater
treatment technologies for mitigating chemical and microbial contaminants,
including both engineered and natural treatment systems. These processes can be
used to tailor wastewater reclamation plants to meet the quality requirements of
intended reuse applications. The concentrations of chemicals and microbial
contaminants in reuse projects designed to augment drinking water supplies can
be comparable to or lower than those commonly present in many drinking water
supplies. The committee emphasized the need for process reliability and careful
monitoring to ensure that all reclaimed water meets the appropriate quality
objectives for its use.
Costs of water reuse for potable and
non-potable applications vary widely because they depend on site-specific
factors, the committee said. Water reuse projects tend to be more expensive
than most water conservation options and less expensive than seawater
desalination and other new supply alternatives. Although the costs of reclaimed
water are often higher than current water sources, the report urges water
authorities to consider other costs and benefits in addition to monetary
expenditures when assessing reuse projects. For example, water reuse systems
used in conjunction with a water conservation program could be effective in
reducing seasonal peak demands on the drinking water system. Depending on the
specific designs and pumping requirements, reuse projects could also have a
larger or smaller carbon footprint than existing supply alternatives or reduce
water flows to downstream users and ecosystems.
Water reuse regulations differ by
state and are not based on risk-assessment methods, the report says.
Adjustments to the federal regulatory framework could help ensure a high level
of public health protection, provide a consistent minimum level of protection
across the nation, and increase public confidence in potable and non-potable
water reuse. The report notes that existing legislative tools could be applied
to improve the quality of water for reuse, including updating the National
Pretreatment Program''s list of priority pollutants to include a wider inventory
of known toxic substances. Also, it lists 14 areas of research to help guide
the country on how to apply water reuse appropriately. Such research would
require improved coordination among federal and nongovernmental
organizations.
The study was sponsored by the U.S.
Environmental Protection Agency, U.S. Bureau of Reclamation, National Science
Foundation, National Water Research Institute, Centers for Disease Control and
Prevention, Water Research Foundation, Orange County Water District, Orange
County Sanitation District, Los Angeles Department of Water and Power, Irvine
Ranch Water District, West Basin Water District, Inland Empire Utilities Agency,
Metropolitan Water District of Southern California, Los Angeles County
Sanitation Districts, and Monterey Regional Water Pollution Control Agency.
The National Academy of Sciences,
National Academy of Engineering, Institute of Medicine, and National Research
Council make up the National Academies. They are independent, nonprofit
institutions that provide science, technology, and health policy advice under an
1863 congressional charter. Panel members, who serve pro bono as volunteers,
are chosen by the Academies for each study based on their expertise and
experience and must satisfy the Academies'' conflict-of-interest standards. The
resulting consensus reports undergo external peer review before completion. For
more information, visit
http://national-academies.org/studycommitteprocess.pdf.
