Issues in Potable Reuse The Viability of Augmenting Drinking Water Supplies with Reclaimed Water (1998) / Chapter Skim
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Executive Summary
Executive Summary
Pages 1-13
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This study assesses the public health implications of using reclaimed water as a component of the potable water supply. It examines the different types of water reuse, discusses considerations for ensuring reliability and for evaluating the suitability of water sources augmented with treated wastewater, and seeks to identify future research needs regarding potable reuse safety testing and health effects When considering potable reuse as an option for public water supplies, a critical distinction must be made between "direct" and "indirect" reuse.
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In communities using reclaimed water where analytical testing, toxicological testing, and epidemiological studies have been conducted, significant health risks have not been identified. This suggests that reclaimed water can likely be used safely to supplement raw water supplies that are subject to further treatment in a drinking water treatment plant.
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From page 3... ...
Potable reuse projects should include multiple, independent barriers that address a broad spectrum of microbiological and organic chemical contaminants. They should also conduct continuous toxicological monitoring if, as a result of the reclaimed water, the drinking water supply contains significant levels of organic contaminants of wastewater origin.
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From page 4... ...
The following recommendations suggest several important guidelines to account for chemical contaminants of potential concern in potable reuse systems: · The research community should study in more detail the organic chemical composition of wastewater and how it is affected by treatment, dilution, soil interaction, and injection into aquifers. The composition of wastewater and the fate of the organic compounds it contains need to be better understood to increase the certainty that health risks of reclaimed water have been adequately controlled through treatment and storage in the environment.
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· Although Safe Drinking Water Act regulations cannot alone ensure the safety of drinking water produced from treated wastewater, potable reuse projects must nonetheless bring contaminant concentrations within those regulations' guidelines. Potable reuse projects can manage regulated contaminants by a combination of secondary or tertiary wastewater treatment processes, dilution or removal in the receiving water, and removal in the drinking water treatment plant.
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Even though classic waterborne bacterial diseases such as dysentery, typhoid, and cholera have dramatically decreased in the United States, Campylobacter, nontyphoid Salmonella, and pathogenic Escherichia cold still cause a significant number of illnesses, and new emerging diseases pose potentially significant health risks. Historically, coliforms, which serve as an adequate treatment indicator or "marker" for many bacterial pathogens of concern, have been used as general indicators of the levels of microbial contamination in drinking water.
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From page 7... ...
Microbiological Methods and Risk Assessment The lack of information nationwide on the levels of viral and protozoan pathogens in all waters and the efficacy of both conventional water treatment and wastewater treatment for water reclamation in removing those pathogens poses challenges to estimating risks from microbial contamination in potable reuse systems. The Information Collection Rule promulgated in 1996 by the EPA should help provide the exposure data needed for more effective risk assessments, but additional steps are needed to improve methods for assessing risks posed by microbial pathogens in water reuse projects: · Potable reuse project managers should consider using some of the newer analytical methods, such as biomolecular methods, as well as additional indicator microorganisms, such as Clostridium perfringens and the F-specific coliphage virus, to screen drinking water sources derived from treated wastewaters.
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From page 8... ...
More research is needed to demonstrate the suitability of these systems for potable reuse applications and to develop monitoring methods capable of continuously assessing system performance. Chemical Risk Assessment Because of the uncertainty of the organic chemical composition of reclaimed water, toxicological testing should be the primary component of chemical risk assessments of potable reuse systems.
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Even a brief look at these studies makes clear the need for a new approach. Toxicology Studies This report includes a review of six planned potable reuse projects that tried to analyze and compare the toxicological properties of reclaimed water to those of the communities' current drinking water supplies.
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From page 10... ...
For reclaimed water, however, the high cost and methodological problems inherent in this approach make it both unreliable and inefficient. Accordingly, a new, alternative testing approach, such as one using fish in source water, should be developed to allow continuous toxicological testing of reclaimed water at reasonable cost.
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From page 11... ...
Therefore, epidemiologic studies should be conducted at the national level using alternative study designs and more sophisticated methods of exposure assessment and outcome measurement to evaluate the potential health risks associated with reclaimed water. Ecologic studies should be conducted for water reuse systems using ground water and surface water in areas with low population mobility.
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· Every community using reclaimed waters as drinking water should implement well-coordinated public health surveillance systems
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From page 13... ...
Further, appropriate interested consumer groups should be involved with and informed about the public health surveillance plan and its purpose. · Finally, operators of water reclamation facilities should receive training regarding the principles of operation of advanced treatment processes, the pathogenic organisms likely to be found in wastewaters, and the relative effectiveness of the various treatment processes in reducing contaminant concentrations.
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