Not Just a Drop in the Bucket: Expanding Access to Point-of-Use Water Treatment Systems Mintz E, Bartram J, Lochery P, Wegelin M ABSTRACT 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 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. 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 limitedquantities 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]. 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