Daniel A. Okun

The value of water supply and sanitation in development: an assessment.

The attractiveness of oral rehydration therapy (ORT), a new and simple ministration that averts many child deaths from diarrhea among children, is diverting attention among donor agencies from the importance of water supply and sanitation (WS&S) in developing nations. The principal factor that led to the adoption of ORT is its apparent low cost per diarrheal death averted in children when compared with WS&S. However, WS&S provides many more benefits that are essential to sustaining the lives saved by ORT and vital to maintaining and enhancing the lives of adults and children. Among many other benefits WS&S prevents spread of the causes of diarrhea, controls many other water- and sanitation-related diseases, releases women from the heavy and time-consuming burden of carrying water from distant sources, and improves the quality of life in the community. Cost comparisons between WS&S and ORT are misleading. WS&S is a long-term investment in preventive health while ORT is a response to an immediate life-threatening situation. WS&S interventions eliminate unsanitary conditions leading to illness and death while ORT has no effect on the causes of diarrheal morbidity. The costs of WS&S are not high:

Water vending activities in developing countries: a case study of Ukunda, Kenya

5 to

Drinking water for the future.

10 per capita annually. Without WS&S and hygiene education ORT programs are not likely to effect long-term improvement in child health status. ORT and WS&S programs are complementary; one should not displace the other.

Water reclamation and nonpotable reuse: an option for meeting urban water supply needs

Millions of people in developing countries obtain water from commercial vendors who deliver it to their homes, yet this phenomenon has received little attention from professionals in the water resources field. This paper describes a water vending system which is in operation in Ukunda, Kenya, a town of about 5000 people south of Mombasa. In this community 45% for water consumed by households is obtained from water vendors who deliver water in carts directly to peoples homes. The prices vendors charge for water are high, but vendors are not making exorbitant profits; hauling water manually is simply expensive. People in Ukunda spend about 9% of their income on vended water, which suggests that there are situations in which households are willing and able to pay substantial amounts of money for water even when traditional sources are readily available.

THE WEAK LINK IN THE PROVISION OF SAFE DRINKING WATER

The Safe Drinking Water Act of 1974 represents an important step in improving the quality of public water supply in the United States. However, it fails to address two important problems: (1) The 1970 Public Health Service Community Water Supply Survey revealed that small public water supply systems often deliver poor quality water. The Act does not assure that these supplies will now receive appropriate attention; furthermore, the Act does not address the needs of the 50 million people not now served by public water systems; (2) About one-third of our population draws its drinking waters from polluted sources. The decisions to use these low cost sources were made generations ago when consumers could be protected from water-borne infectious disease. A new problem has now arisen--the presence of numerous synthetic organic chemicals of uncertain health consequence, not removed by conventional water treatment. The Act does not address this problem. Regionalization and the integration of water resource and water pollution control authorities are proposed as a reasonable solution to these problems. The development of dual water supply systems in order to conserve scarce pure water sources for human consumption appears to be a feasible way to avoid using polluted waters for drinking. The development of dual supplies would be enhanced by regionalization and integration of water authorities.

The Role of Reclamation and Reuse in Addressing Community Water Needs in Israel and the West Bank

Abstract The theme of this paper is that the reclamation of wastewater for nonpotable purposes in urban areas constitutes a new water resource; the need for additional urban supply will become the driving force for its adoption in the future. As the several alternatives available to a municipality for adding to its public water supply are being considered, one option that should be fully explored is wastewater reclamation for nonpotable urban uses.

The Evolution of the Environmental Engineer

The provision of safe drinking requires high quality water sources, treatment of the water, and its distribution. However, the first distribution systems in cities were designed for fire protection. In time they were extended to commercial and then to residential properties but their design then was the responsibility of the National Board of Fire Underwriters. Today, it is the Insurance Services Office, Inc., whose regulations are the text of AWWAs Manual M31, Distribution System Requirements for Fire Protection. Not one word relates to drinking water quality. Its only purpose is to assure adequate pressure and flows for fire protection. Apparently, drinking water quality is of no importance. Recent AWWA Water Quality Technology Conferences have had hundreds of papers on the degradation of water quality in distribution systems. Last year, AWWA compiled a 1,083-page volume, Water Quality in the Distribution System. The problems arise from defects in distribution systems designed for fire protection. Pipes and storage tanks need to be larger than necessary for drinking water systems, resulting in residence times that range to months. Long residence makes many water quality problems. Difficulties in maintaining disinfection, demanding higher doses of disinfectant, in turn result in excessive levels of disinfection by-products (DBPs), which are the most serious water quality health problems extant today. Another problem created by long residence times is the growth of biofilm on the insides of the pipes. The biofilms react with the disinfectants ,reducing their and creating growths that harbor the pathogens This leads to tuberculation that in time reduces the hydraulic capacity of the pipes. Still another problem created by the minimum 6- and 8-inch diameter pipes, which make up the larger lengths of pipes in the systems, are heavy pipes laid on soil with some 350 joints per mile, many of which, in time, leak. Loss of water may not be serious, but the frequent negative transient pressures that occur in the pipes have been found to suck contaminated groundwater into the pipe. One solution is a distribution system that carries only drinking water. It would not have hydrants and in most of the city, the pipes would be less than one inch, and laid with few joints. It would be a drinking water distribution system with none of the problems we face today. What about fire protection? In the last half-century, dual water systems have spread over the country. They were created to conserve drinking water by using reclaimed wastewater for the many nonpotable demands, including water for fire protection. More than 2,000 cities and towns have dual systems and more are being created every day. Most conventional water treatment plants are far short of being adequate despite statements that they meet EPA regulations. If only drinking water needs to be treated, the far lower cost would permit the adoption of membrane treatment, assuring drinking water of high quality Without question, new communities adopting such dual systems would deliver much higher quality water at lower cost. For existing communities, distribution systems would need to be introduced gradually when retrofitting for growth and as funds are available.

Surface Water Treatment for Communities in Developing Countries

Publisher Summary This chapter discusses the role of reclamation and reuse in addressing community water needs in Israel and the West Bank. The reclamation of wastewater and its reuse for the myriad nonpotable purposes that can be met by water of less than potable quality has proven to be an environmentally and economically attractive option for addressing local and regional shortages throughout the United States. Various advantages of urban over agricultural reuse have been presented. Urban reuse often involves dual distribution systems, one system delivering water drawn from fresh water sources for potable uses and the other drawn from reclaimed wastewater for nonpotable uses. Urban uses of reclaimed water include (1) cooling, (2) toilet flushing, (3) cleansing, and (4) groundwater recharge. Reclamation plants differ from treatment plants, which are intended only for disposal of effluent to receiving waters, in various ways, such as the location of the plant is influenced by potential markets for the reclaimed water rather than by disposal and receiving water requirements.

Distributing reclaimed water through dual systems

Sanitary engineers emerged in the late 19th century with the responsibility for providing safe water and proper sanitation to promote and protect the public health. Their work contributed substantially to the virtual elimination of water-borne infectious diseases, such as cholera and typhoid, in the industrialized world. With the chemical revolution a century later, a new health threat arose from the long-term ingestion of trace concentrations of synthetic organic chemicals in water supplies drawn from polluted sources. Simultaneously, air and soil pollution also threatened the public health with chronic disease. These chemicals were also perceived as degrading the natural environment, threatening all biota. The environmental engineer evolved from the sanitary engineer but was obliged to work with scientists and engineers from a wide range of disciplines.