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COMMENTARY |
Eric Mintz is with the Foodborne and Diarrheal Diseases Branch, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Ga. Jamie Bartram is with Water, Sanitation, and Health, World Health Organization, Geneva, Switzerland. Peter Lochery is with Water, Sanitation, and Environmental Health, CARE, Atlanta, Ga. Martin Wegelin is with the Department of Water and Sanitation in Developing Countries, Swiss Federal Institute for Environmental Science and Technology, Duebendorf, Switzerland.
Correspondence: Requests for reprints should be sent to Eric D. Mintz, MD, MPH, Mailstop A-38, Centers for Disease Control and Prevention, Atlanta, GA 30333 (e-mail: ).
| ABSTRACT |
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Since 1990, the number of people without access to safe water sources has remained constant at approximately 1.1 billion, of whom approximately 2.2 million die of waterborne disease each year. In developing countries, population growth and migrations strain existing water and sanitary infrastructure and complicate planning and construction of new infrastructure.
Providing safe water for all is a long-term goal; however, relying only on time- and resource-intensive centralized solutions such as piped, treated water will leave hundreds of millions of people without safe water far into the future. Self-sustaining, decentralized approaches to making drinking water safe, including point-of-use chemical and solar disinfection, safe water storage, and behavioral change, have been widely field-tested. These options target the most affected, enhance health, contribute to development and productivity, and merit far greater priority for rapid implementation.
| INTRODUCTION |
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We continue to allocate more money to conflict than to services, prestige projects take precedence over more mundane services, and populations without water and sanitation have neither the contacts nor the power to exert any influence. . . . [That] we have been unable or unwilling to ensure the access of one-quarter of the world's population to a safe supply of water and one-half of the world's population to adequate excreta disposal is among the most glaring examples of a failure to apply basic scientific principles to protect human health.
Paul Taylor1
WATER IS ESSENTIAL TO LIFE. We drink it, raise crops and livestock with it, clean our bodies and environment with it, and play in it. When it is contaminated with human or animal wastes, however, water carries illness and death. Approximately 1.1 billion persons, or one sixth of the world's population, lack access to safe water sources, and many more lack access to safe water.2
Important diseases that can be transmitted by the waterborne route include cholera, typhoid fever, amoebic and bacillary dysentery, and other diarrheal diseases; these diseases, which cause an estimated 2 187 000 deaths worldwide each year (A. Pruess, MPH; World Health Organization; written communication; May 10, 2001), account for most water-associated morbidity and mortality. Other contributors include (1) the water-washed diseases (e.g., scabies, trachoma), caused by poor personal hygiene and preventable through improved access to safe water; (2) the water-based diseases, caused by parasites found in intermediate organisms living in water (e.g., dracunculiasis, schistosomiasis); and (3) the water-related diseases, caused by insect vectors that breed in water (e.g., dengue, malaria).3 The direct health burden is supplemented by the annual expenditure of over 10 million person-years of time and effort by persons carrying water from distant and often polluted sources.4 In addition, indigent populations often pay exorbitant prices for limited quantities of poor-quality water, at costs that can represent 20% of a family budget,5 while services to wealthier urban dwellers are heavily subsidized and of relatively high quality.6 The claim has been made that no single type of intervention has greater overall impact on national development and public health than does the provision of safe drinking water and the proper disposal of human excreta.4
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In 1980, the United Nations General Assembly proclaimed the period 1981 to 1990 as the International Drinking Water Supply and Sanitation Decade, with the primary goal of full access to water supplies and sanitation for all.6 During the course of that decade, access to safe water was provided to an additional 1347 million people and access to sanitation facilities was provided to an estimated 748 million, at an estimated cost of US $133.9 billion.6 Despite these major accomplishments, by the decade's end more than 1.1 billion people still lacked access to safe water and 2.4 billion were without adequate sanitation.2 Reasons cited for the decade's failure to achieve more include population growth (estimated at 750 million), funding limitations, inadequate operation and maintenance, inadequate cost recovery, insufficient trained personnel,7 and continuation of a "business as usual approach," drawing on traditional policies, resources, and technologies.6 In particular, little progress was made in providing services to rapidly expanding, low-income, marginalized urban populations and to rural areas.6,7 The most recent assessment of water supply and sanitation coverage shows that although more people than ever have access to water supply and sanitation services, the absolute numbers of unserved people remained constant throughout the period 1990 to 2000, when 1.1 billion were without access to improved water sources and 2.4 billion lacked access to basic sanitation.2
Water treatment plants and other large-scale projects remain an important and necessary objective of many development agencies; they were major advances in the sanitary revolution in industrialized countries at the end of the 19th century.8 A century later, providing safe piped water to dispersed populations in rural areas of developing countries can be prohibitively expensive for governments, donors, and private utilities, calling into question the sustainability of this approach and whether anticipated health gains will be achieved, even from large investments. Meanwhile, in urban areas, rapid population growth and migrations motivated by cultural, economic, political, and environmental factors strain existing water and sanitary infrastructures and create enormous problems in planning and constructing new infrastructure. Residents of many of the world's largest cities enjoy only intermittent access to piped water, often of dubious quality and only from public taps at substantial distances from their homes. Others depend on water vendors for small volumes of costly water of unsure quality. Where providers cannot guarantee water quality at the point of supply, or where it cannot be guaranteed at the point of use, because of contamination during collection, transport, and storage, consumers face significant health risks.
Given the failure to reduce the numbers of people without access to basic water supply and sanitation during the 1990s, and the financial implications of even the apparently modest international development target of halving the proportion of people not served with improved drinking water by 2015 (A. Pruess, MPH, written communication, May 10, 2001), it is evident that "business as usual" cannot provide a satisfactory response. Approaches that rely solely on time- and resource-intensive centralized solutions will leave hundreds of millions of people without access to safe water far into the foreseeable future; a radical reorientation toward interventions to support these populations is urgently required. This commentary reviews 2 low-cost decentralized technologies used to improve drinking water quality in developing countries and considers the role these technologies may play in future efforts to provide safe drinking water for all.
| POINT-OF-USE CHEMICAL DISINFECTION |
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In the past 5 years, several published field trials of hypochlorite for point-of-use water treatment have established that it is acceptable for and effective at improving water quality in a number of settings, and that its use can reduce diarrheal illness by up to 85%.1519 It has been used to improve the safety of oral rehydration solutions and street-vended beverages,20,21 and, as described in this issue, as an emergency response measure for persons displaced by natural disasters and threatened by epidemic cholera.13, 22, 23 Among the limitations of hypochlorite-based disinfectants are their relative ineffectiveness against parasites and viruses and the reduced efficiency and disagreeable taste or odor that may result when they are used to treat water with excessive amounts of organic material.12, 14 In their favor are the protective residual effect against bacterial contamination and the fact that they can be easily and reliably quantified in treated water by simple and inexpensive colorimetric assays.
| POINT-OF-USE SOLAR DISINFECTION |
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"Approaches that rely solely on time- and resource-intensive centralized solutions will leave hundreds of millions of people without access to safe water far into the foreseeable future."
Field trials of solar disinfection in Kenya demonstrated that it was an acceptable and effective means of improving water quality and significantly reduced the incidence of diarrhea and severe diarrhea in children.31,32 Other health impact studies are under way. The limitations of solar disinfection are the need for sufficient solar radiation and relatively clear water and the difficulty in treating large volumes. Its advantages are simplicity, extremely low cost, and the fact that it leaves the taste of water unchanged.
| SAFE WATER STORAGE |
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The principles of safe water storage, the characteristics of safe water storage vessels, and early intervention studies evaluating these vessels have been reviewed.12 Safe water storage vessels with tight-fitting lids and narrow mouths, which allow users to remove water by pouring or through spigots but not by dipping, have been incorporated into both chemical and solar water treatment programs.28, 44 The articles in this issue by Makutsa et al.14 and Ogutu et al.45 highlight the challenges of creating water storage vessels that meet traditional cultural standards and still fulfill the role of adequately protecting treated water from recontamination.
| BEHAVIORAL CHANGE |
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Improvements in the quality of drinking water provide far more benefit when coupled with improvements in hygiene and sanitation.48, 49 Introducing treated drinking water into households in storage vessels with spigots or spouts enables families to reduce their exposure to waterborne pathogens and, in conjunction with hand washing and soap promotion, provides a platform for reducing the risk of water-washed diseases.50 Safe storage of water in covered or closed containers may significantly reduce contamination by host organisms for the parasitic causes of water-based diseases and by mosquito vectors of water-related diseases such as dengue. Finally, safe water and, if available, hypochlorite disinfectant can be used for washing fruits, vegetables, and other foods consumed raw, thereby potentially reducing the incidence of food-borne infections.
| THE ROLE OF LOW-COST, APPROPRIATE TECHNOLOGIES |
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Safe water storage vessels with tightfitting lids and narrow mouths have been incorporated into both chemical and solar water treatment programs.
The problems of unsafe water and poor sanitation demand a multitude of varied and complementary solutions. In most areas, available options for point-of-use water treatment are limited and ineffective at preventing disease (filtration, sedimentation) or inconvenient and prohibitively expensive (boiling). Point-of-use programs in several countries have demonstrated that the market for safe water will readily absorb more effective treatment options if these are reasonably priced and properly promoted.44
We are witnessing unprecedented experimentation with new forms of privatization worldwide and increased attention to accountability and performance. People are increasingly perceived as consumers, rather than recipients, of development. Recognition of this trend favors an emphasis on consumer choice and a more pluralistic approach toward water safety, with an increasing number of options of varying costs, convenience, and effectiveness more widely available.1 Field trials, such as the ones reported in this issue from Kenya14,45 and Madagascar,13,22,23 can help define the optimal use of each of these options.
Cellular phones and satellite dishes revolutionized the telecommunications industry in developing countries, bypassing the expenditures and delays associated with traditional wire-based systems and allowing consumers rapid access to phone and television service. Similarly new scientific research and the current global economic and political climate offer dramatic opportunities to introduce new decentralized approaches for improving water quality. Capitalizing on these opportunities requires unique partnerships between the private and public sectors that can be brokered by the donor community. Multinational consumer products firms that produce, market, and distribute soap, bleach, and vessels suitable for safe water storage are well positioned to participate in this new sanitary revolution. But many barriers still need to be overcome and much work remains to be done before safe water is made as widely available as tobacco, alcohol, or carbonated soft drinks.
| CONCLUSIONS |
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| Acknowledgments |
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| Footnotes |
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Note. The views expressed in this commentary do not necessarily represent the decisions or the stated policy of the World Health Organization.
Accepted for publication June 5, 2001.
| References |
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