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Global Environmental Health: Research Gaps and Barriers for Providing Sustainable Water, Sanitation, and Hygiene Services - Workshop Summary
3
The Technology Pillar of Sustainable Water: Technology, Economics, and Health
Approximately 1.1 billion people worldwide are currently without access to safe drinking water. Addressing this need in a sustainable way is one of the overarching challenges of the international community and may be the difference between security and instability, between opportunity and poverty. A cornerstone to approaching this challenge is the appropriate use of new and existing technology. This chapter captures the presentations from the workshop on how technology, water management, and community engagement can ensure human health.
MOVING TOWARD MEGACITIES: DECENTRALIZED SYSTEMS
Asit K. Biswas, Sc.D., President and Academician
Third World Centre for Water Management
Many people have asserted that the 21st will be the century of water and there will be significant conflicts because of the lack of water. The fundamental assumption behind the idea of water scarcity that people make is that water is like oil: once you use it, it’s gone. In fact, water can be used, recycled, and reused a number of times. For example, each drop of the Colorado River is used at least seven times. With better management practices, this number can increase.
In 2006, the United Nations Development Programme released a Human Development Report on water for the first time. The city named as having the best water supply and wastewater treatment was not in the United States, Europe, Australasia, or Japan—but was Singapore, a city with one of the lowest per capita water supplies.
Singapore has two agreements to bring water from Malaysia that are due to expire in 2011 and 2058. The Singaporeans have already given advanced notice to the Malaysian government that they do not want to renew their 2011 treaty. Their water delivery strategy has shifted from water procurement to managing
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the resource better. A central component to their plan is to use treated wastewater for drinking and to sell wastewater to the semiconductor industry. Using recycled water as drinking water can create a perception problem. However, there is a top-down commitment in Singapore, as the president and the prime minister drink the “new water” (i.e., recycled, domestic wastewater). In general, there is widespread acceptance because of the quality of the water, irrespective of religion.
There will not be a shortage in the availability of water unless there continues to be mismanagement of current resources. This can be true not only in all regions, but also in the world’s megacities—cities with more than 10 million inhabitants. Currently in Delhi, the water board supplies water for three hours a day. Due to this inefficiency, each house or block of flats in Delhi is a mini-utility. They collect enough water to last for 24 hours by using underground storage tanks under each house or block of flats.
In Delhi, water consumption is 250 liters per capita per day; however, approximately 50 percent of this water is not accounted for. As in many regions in the world, 40–70 percent of the water pumped into the system never reaches the consumer (Biswas, 2006) because of leakage and pilferages. This is true not only in developing countries, but also developed countries. In 2006 Thames Water, one of the largest private water supply companies in the United Kingdom, lost 31 percent of its water before it reached the consumer. Singapore is the one bright beacon, with losses amounting to approximately 5 percent.
Furthermore, the water crisis is going to come, not from the shortage of water, but because of decades of negligence for water quality management. To illustrate: In 1976, during the International Water Supply and Sanitation Decade, the United Nations General Assembly approved the idea that access to water means access to water that is drinkable. In Delhi, however, each house or block of flats has had to set up such processes as reverse osmosis or a membrane system, because the filtration supplied is not sufficient to make the water drinkable. The intention of the Millennium Development Goals (MDGs) and the International Water Supply and Sanitation Decade is that people should receive water that is potable. They should not have to set up a mini-utility to ensure that their water is drinkable. MDGs state that, between 1990 and 2015, the number of people who do not have access to water should be reduced by 50 percent. Although there is a concerted effort to meet these goals, the fundamental question is whether the water that people are being supplied is drinkable. Or are small Delhi experiences being set up around the world?
Sanitation is another challenge for MDGs, which state that, between 1990 and 2015, the number of people without access to sanitation should be reduced by half. (Sanitation was not an original component of MDGs: it was added by the Johannesburg Declaration of 2002.) While this is a laudable goal and progress is being made to reach it, this is not the full story. From Mexico City to Delhi, from Manila to Nairobi, wastewater is collected from houses, but most of the time there
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is not even primary treatment of it. This untreated wastewater discharge simply transfers the problem from one place to another.
There is a lack of accurate numbers to answer the question of what percentage of people have access to sanitation and what percentage have access to sanitation and wastewater treatment. Solid statistics do not exist in this area. In Latin America, approximately 40–50 percent of people have access to sanitation, but approximately 11 percent have access to wastewater treatment and proper wastewater disposal. What this means is that places like Sao Paulo, Mexico City, Delhi, and others are either dumping their wastewater into the ocean, onto the ground, or into other bodies of water. The current situation of most urban centers in the developing world is that most of the water courses in and around the major cities are heavily polluted. The extent and the type of pollutants are not known, as there is a lack of information on water quality to holistically examine the water issue.
Financial issues and lack of expertise are not the largest challenge facing megacities; it is the need to improve management and harness the political will. Another problem is that there is inertia among the public. Some people accept the current standard as the status quo and do not push for necessary infrastructure and management improvements. The improvements may not necessarily need new knowledge generation, but rather knowledge synthesis. This approach would require a detailed understanding of what technologies or strategies work where and under which environmental and cultural conditions. For example, the city of Phnom Penh was losing 80 percent of its water in 1993. The Phnom Penh Water Supply Corporation was broke and had little staff or office space. In a time span of 14 years, the Phnom Penh Water Supply Corporation has become fully independent and now only loses approximately 8 percent of its water through better management of resources and synthesis of current knowledge. Delhi, Mumbai, and Nairobi have enough water. All they need is how to effectively use their current water resources. Kenya’s second largest city, Mombasa, can support itself by the unaccounted for water of its major city, Nairobi.
The final point is pricing. Without full-cost pricing, there is no other way to supply clean water and wastewater treatment. In conclusion, the world does not have a problem with the lack of available water. There is enough science and management expertise, but its use is not being maximized. And if people do not use their current resources appropriately, even with access to all the water in the world, there will still be the same problem.
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OVERVIEW OF THE WATER SECTOR: POLICIES, INSTITUTIONAL ROLES, AND KEY ISSUES FOR UTILITY SERVICES DELIVERED IN GHANA
Eric Kofi Obutey, M.B.A., Economist and Manager
Public Utilities Regulatory Commission, Ghana
Ghana is located in the western part of Africa, bordering the Ivory Coast, Togo, Burkina Faso, and the Gulf of Guinea. The country has a population of 22 million, with 57 percent rural and 43 percent urban inhabitants and a life expectancy of about 56 years. The gross domestic product per capita is approximately $400. In urban areas, 58 percent of the population receives some water services, and in rural areas and small towns, water coverage is 53 percent.
Water services are covered by a multitude of institutional arrangements in the government (see Figure 3-1). The Ministry of Water Resources, Works, and Housing administers policy, planning, and some aspects of financing. The Ministry of Finance covers some of the financial services. In addition, the Ghana Water Company, Ltd. (GWCL) oversees the urban water systems, and the Community Water and Sanitation Agency (CWSA) oversees the small town and rural systems and functions as a policy advisory body for the small town systems. Although the urban water supply is managed by the publicly owned utility company—the government and GWCL—the operations have been ceded to Aqua Vitra (AVRL).
FIGURE 3-1 Institutional arrangement of agencies covering water services in the Ghanian Government.
SOURCE: E.K. Obutey.
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AVRL operates 87 systems in the 10 water regions. The remainder of the communities in the small towns and rural systems have established water boards and private operators with service contracts. Complementing the major agencies are several other government agencies that assist with regulatory affairs.
GWCL has approximately 364,000 billed customers. The nonrevenue water is 48.8 percent. The company has a daily average production of 580,000 cubic meters with an effective metering ratio of 47 percent. Tariffs alone do not cover the $1.5 billion needed to have an effective system, so the government is trying to mobilize investments.
Public Utilities Regulatory Commission of Ghana
The Public Utilities Regulatory Commission (PURC) of Ghana has produced three regulations since its inception in 1997: one to address the termination of service, one for a complaints procedure, and a third for the establishment of a customer service committee. For example, legislative instrument 1651 establishes the rules and regulations under which the company can terminate the services to a person. PURC has also published two important policy documents: the Social Policy Document for Water Regulations and the Urban Water Tariff Policy. Furthermore, by recognizing the large number of agencies involved in supplying fresh water, the commission has developed a Drinking Water Safety Plan to regulate water in a holistic manner—from the source to the consumer. Finally, the commission oversees three pilot projects to determine how to best serve the poor in society, with the goal to replicate these projects throughout the country.
National Development Goals
Recognizing the health and economic implications of ensuring adequate water services for the people of Ghana, the government laid out the National Development Goals in the Growth and Poverty Reduction Strategy II, a document that outlines strategies to accelerate water delivery in urban areas. As part of the goals, the government is seeking to establish PURC regional offices in all regions beyond the 10 currently served, mobilize new investments for urban water systems, extend distribution networks with an emphasis on the poor, and strengthen the management of the GWCL.
For the urban poor, there have been provisions of standpipes that allow some accessibility to water services, allowing people to draw water. The Growth and Poverty Reduction Strategy addressed the commission’s transition to bring tariffs to cost recovery to make the operations of the urban water systems sustainable, at the same time assessing the lifeline tariff for poor urban households. In the transition, there was recognition that the tariffs had to be incrementally brought to the full-cost recovery level. Furthermore, the goals helped to direct state interventions in areas in which there is a marked gap in service delivery.
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National Water Policy
Currently, PURC has a draft National Water Policy with four broad principles. First, at its core, the policy establishes the fundamental human rights of all people, without discrimination, to have access to safe and adequate water to meet their basic human needs. Second, it states that water is a finite and vulnerable resource, with multiple uses. Third, it outlines the principle of solidarity—expressing profound human alliance to solve common problems related to water. Fourth, it meets social needs for water as a priority by recognizing the economic value of water and the goods and services it provides. As part of its strategy to ensure water, the policy has created an outreach program to educate the public to not waste water and established the Water Resources Commission to manage the water resource.
The key policy objectives for water resources management are to achieve sustainable use, while maintaining the biodiversity and the quality of the environment for future generations. The Water Resource Commission achieves this through protection, from the original source water all the way through the water delivery system. In the rural/small town water system, the overall objective of PURC is to improve the public health and economic well-being of rural and small town communities through water, sanitation, and hygiene education interventions. The specific objective includes the provision of basic water and sanitation services for communities that will contribute to the capital cost and ensure payment for normal operations and maintenance, at the same time being mindful of the need to ensure affordability, equity, and fairness for poor and vulnerable populations. The policy also sets out strategies to ensure sustainability through effective community ownership and management. There is a role for various forms of participation, and part of the strategy creates opportunities for the private sector to grow. For example, before the management contract with AVRL, the government considered several options. The current management contract runs for five years with the option of a five-year extension. If the extension does not happen, the operations will revert back to the government of Ghana.
Finally, the draft National Water Policy sets out to achieve financial sustainability through full-cost recovery. However, the policy is mindful of the need to apply cross-subsidies and design interventions to suit the supply and payment choices of the poor. The government cannot retrieve all the costs of running the company through the tariffs, so alternatives for investments are being explored.
Draft National Water Policy II
The draft National Water Policy II focuses on two key issues: equity and secondary and tertiary providers. The policy has a stated commitment to having an equitable amount of investment resources dedicated to extending services to low-income communities. Access to water services is a health issue, owing in particular to typhoid and Guinea worm infection. The government is looking at the
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best consortium investment to extend services to low-income areas, but they need to address the basic problem that individuals need to pay the connection fee.
In 2006, approximately 50.4 percent of rural water services was financed by the developing partners, and only 1.5 percent was supported by the government of Ghana. For the urban water supply, 34.7 percent was financed by the development partners, and approximately 1.7 percent was supported by the government. In order to meet the Millennium Development Goals, Ghana needs $820 million to meet the 2015 targets, an average $85 million a year. For the rural systems, the need is less—approximately $756 million. Figure 3-2 shows the commitment by the government of Ghana to reduce poverty in various sectors in 2003 and 2004. There has been a slight shift in funding toward feeder roads, agriculture, and rural electrification, away from water services, basic education, and primary health. So the challenge is how the country, with its multiple priorities, can address this major issue.
In summary, the government is faced with a number of key issues. Financing will continue to be a need, and the government is approaching this by identifying the needed investments and establishing roles for consumers, the government, and the development groups. The plans that are being drafted need to be equitable for all regions and socioeconomic groups, with increased commitment to the
FIGURE 3-2 The percentage of money by sector allocated by the government of Ghana to reduce poverty in 2003 and 2004.
NOTE: PRE = poverty reduction expenditures; WSS = water supply and sanitation.
SOURCE: Derived from PURC, 2005; Ministry of Water Resources, Works, and Housing, 2007; IMF, The World Bank, 2005. Ghana: Poverty Reduction Strategy Paper Annual Progress Report by E.K. Obutey.
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underserved and the urban poor. Management plans will be important to interface between the urban and rural systems and for protecting natural resources. Finally, monitoring and evaluation need to be strengthened.
CLEAN DRINKING WATER: SOLVING THE ARSENIC CRISIS IN BANGLADESH THROUGH A SUSTAINABLE LOCAL FILTRATION TECHNOLOGY
Abul Hussam, Ph.D., Professor
George Mason University
The U.S. Environmental Protection Agency (EPA), the World Health Organization (WHO), and the government of Bangladesh have standards for drinking water quality with regard to inorganic, organic, and microbial species. Drinking water should be free from pathogenic microbes and from toxic inorganic species, like arsenic. For many regions of the world, achieving this goal is a challenge. For example, the occurrence of toxic arsenic species in groundwater used for drinking is pervasive in the Indian Subcontinent, Southeast Asia, South America, Africa, Central America, and North America. The acceptable limit in potable water as set by the EPA is 10 parts per billion (or 10 micrograms per liter). A significant number of areas in the United States and around the world exceed this limit in their groundwater (Figure 3-3).
Bangladesh: The Challenge of Providing Potable Water
Bangladesh is a country of many rivers, but these waters are not potable because the surface waters are often polluted with high levels of pathogenic bacteria. For the past two decades, United Nations Children’s Fund (UNICEF) and the World Bank have funded the installation of approximately 10 million tube wells to circumvent this problem. One well-known unintended consequence of this development is that 30 percent of these tube wells have water with high levels of arsenic. Drinking arsenic-contaminated water for a long time causes such illnesses as hyperkeratosis on the palms or feet, fatigue, and cancer of the bladder, skin, or other organs. The human liver degenerates at 800 parts per billion (ppb) of arsenic, but some experiments in mice suggest that degeneration can start as low as 10 ppb. A typical arsenicosis patient is shown in Figure 3-4. Naturally occurring arsenic in groundwater is now regarded as one of the most harmful public health crises in the world (Mukherjee et al., 2006).
More than 1 million people now have arsenic skin lesions (Smedley and Kinniburgh, 2002). Although the estimates for contamination vary, between 77 and 95 million people in Bangladesh are affected by high levels of arsenic in their drinking water. The problem is not uniformly distributed, but the local hot spots are densely populated. It is interesting to note that one tube well can have 50 ppb
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FIGURE 3-3 Arsenic in groundwater is a pervasive problem throughout the world. A significant number of locations exceeds the 10 parts per billion set by the U.S. EPA.
SOURCE: Smedley, P., and D.G. Kinniburgh, 2002. A review of the source, behaviour and distribution of arsenic in natural water. Applied Geochemistry 17(5):517-568. Reprinted with permission from Elsevier and British Geological Survey.
FIGURE 3-4 Arsenicosis patient showing hyperkeratosis on the palms.
SOURCE: A. Hussam.
and a tube well less than 100 feet away can have 170 ppb. In all, 16 percent of the deep tube wells in Bangladesh and India are contaminated. Scientists cannot accurately determine where to place tube wells to obtain arsenic-free water. The arsenic concentration also increases, albeit relatively slowly, as the age of the tube well increases. The initial draw from the tube wells can be deceptive—appearing to be of adequate quality, but with high concentrations of iron and arsenic. The water starts to become turbid through a process of oxidization and self-attenuation (Figure 3-5).
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FIGURE 3-5 Water that appears to be of high quality (right) upon initial draw from the tube well can contain high concentrations of iron and arsenic—the water starts to become turbid (left) through a process of oxidization and self-attenuation.
SOURCE: Hussam, 2008. Clean drinking water: Solving arsenic crisis through a sustainable local filtration technology. Global Environmental Health: Research Gaps and Barriers for Providing Sustainable Water, Sanitation, and Hygiene Services, Washington, DC.
The origin and distribution of arsenic in groundwater is still under study. However, early indications show that a biogeochemical reduction process mobilizes the arsenic in the ground into a form that is present in water. Current theory suggests that an anaerobic bacterium is consuming iron and organic matter present in the young geological formation; it is then using the iodine present in soil to convert and dislodge the stable form of arsenic into an unstable form called arsenite. Arsenite, the most toxic form of arsenic, is now in solution and contaminates the wells.
Toxicity of Arsenic Compounds in Decreasing Order
Strategies to Address the Problem
Because bringing water from the rivers miles away is not a plausible solution, scientists have been looking for more natural solutions to remove toxic forms
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of arsenic by understanding its chemistry and interaction with the environment. Surface water does not often contain arsenic, even when there is arsenic in the surrounding soil, because the soil absorbs the arsenic through a complex mineralization process with iron. Scientists have been trying to use zero-valent iron to absorb arsenic, similar to the method that soil mitigates arsenic.
One of the first systems used is a three-pitcher system to filter contaminated groundwater. The top pitcher contains sand at the top, cast-iron turnings in the middle, and sand at the bottom; this is the active filter to remove arsenic and other toxic species. The second pitcher is a sand-charcoal-sand-gravel filter, which removes residues from the first pitcher. The third pitcher is the collector for the filtered water. This system was tested in Nepal and in Bangladesh under a national environmental technology verification program for arsenic mitigation. It was demonstrated to produce high-quality water as defined by various government standards. This sustainable filtering system proved to be comparable in quality to commercially made filters containing active materials, such as microfine iron oxide, activated alumina, and hydrous cerium oxide in ion-exchange resins.
Later versions improved on the design to create a two-stage filtration system (Figure 3-6) of sand, composite iron matrix (CIM), and charcoal. This system has a flow of approximately 20–60 liters per hour, with the effluent water having less than 10 ppb of arsenic, which is below the EPA limit. As noted above, water contains two different arsenic species, As(III) and As(V), in which As(III) is 1,000 times more toxic. In this system, As(III) concentrations are removed to less than 2 ppb, which is below the detection limit of the measuring instruments and much below the toxicity level of 10 ppb.
The filter is guaranteed to work for five years, and its maintenance is extremely low. The only maintenance procedure is needed if there is soluble iron in the groundwater, usually more than 5 milligrams per liter, because the iron hydroxide precipitate might decrease the flow rate. The user needs to wash the precipitate off the sand and put the sand back into the system or use new sand. The cost of one filter is approximately $35–$40. Furthermore, these filters also produce water with significantly less manganese, iron, barium, and other inorganic species to make water potable to national standard. Building on the success of these first filters, there are plans to develop small filtration units in areas where arsenic is not a problem—for example, in Dhaka City, where the groundwater has high concentrations of iron, barium, calcium, and manganese, often resulting in nonpotable water.
This filter is built with an eye toward sustainability. It is a green filter, which means that the active material, composite iron matrix, is nontoxic. It can be disposed in the open, because it is converted into some minerals similar to what is naturally present in soil. At the end of the five-year filter life span, the CIM can be turned into metallic iron by a local blacksmith or it can be recycled into CIM by the manufacturer. The latter is a more attractive option because of the possible scarcity of iron in the future. Thus nothing is wasted. The use of the filters
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Among a number of challenges to this program, one of the largest was the perception by the government that the population in these communities would not be interested or participate. Community engagement was an important component of the project, and one facet was to select or have the community select a representative. These individuals underwent one of two types of training, as either operator or administrator of small potable water systems. The operator training was 1 year in duration and consisted of at least 12 hours per week in the practical work in the communities. In the operator training, the modules included source protection, technical operation skills, and how various components of the system (source water, treatment, and distribution) related to each other. The administrator training was nine months in duration and included basic understanding of potable water system operation.
During the baseline period, the community was engaged in the planning of the system assessment and monitoring. The health-based targets were based on the project’s Water Safety Framework. In addition, there were some independent surveillance studies.
The project was conducted in two different areas of Puerto Rico, although the results presented here are from Patillas, which is located in southwestern Puerto Rico. A cooperative of small systems was established, consisting of 8–10 small systems. The idea was to intervene in system operation, making some improvements, conduct a pathogen study, and complete a health assessment. Those studies were done before, during, and after the intervention.
The pathogen study focused on Salmonella and used a simple protocol in which 10 liters of water were filtered, and then the filters were divided among three laboratories (University of Delaware, Washington College, and the Center for Education, Conservation and Environmental Interpretation, Inter American University of Puerto Rico). These preliminary results showed that Salmonella was present 13 of 15 raw water and 22 of 37 distributed water samples. The occurrence of Salmonella was not significantly correlated with total coliform, fecal coliform, or E. coli. In the pilot program, there was a strong effect of education (training of the operators), with a significant decrease in Salmonella occurrence and diarrheal disease after the educational intervention. The decrease in diarrheal disease was stronger in both the elderly and children, and the preliminary results showed that 43 percent of diarrheal disease in the control communities was due to contaminated drinking water.
Furthermore, contrary to the initial perceptions, communities are willing to participate in strategies to improve their health and make their water supplies sustainable. Education and community commitment are key factors in reaching these goals. As evidence of this commitment, a follow-up case-cohort study showed that the reduction in the incidence of the diarrheal disease in communities with the intervention was maintained after 18 months, and the control systems without the intervention showed approximately the same incidence of diarrheal disease as the systems in the initial study before the intervention.
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THE USE OF TECHNOLOGIES: EXPOSURE (CROSS-CONTAMINATION), RISK ASSESSMENT, AND GUIDELINES
Nicholas Ashbolt, Ph.D., Senior Research Microbiologist
National Exposure Research Laboratory, U.S. Environmental Protection Agency
Whereas the focus of various governments and nongovernmental organizations has been on whether people have access to a tap or a standpipe for water, a number of technology advances are of concern to health practitioners. Some of these technologies can result in exposure to pathogens through cross-contamination or growth within distribution systems, and others can have a more direct exposure pathway.
Opportunities to Rethink Water Services
Globally, both developed and developing governments and public utilities have a major problem from neglecting the water infrastructure. Some estimates suggest that at least 80 percent of the total cost of water and sanitation services is for infrastructure, the remaining 20 percent being for treatment. However, with an annual estimated shortfall in maintaining that infrastructure in the United States of some 20 billion dollars, some people in the water services field see an opportunity to rethink the current system as the aging infrastructure is renewed. This presentation highlights a number of opportunities.
One opportunity is to make water “fit-for-purpose” for which it is used. For example, at one end of the quality spectrum, advanced-treated wastewater in Singapore is returned to the source water reservoir, blended with other river water and conventionally treated at the waterworks, with approximately 10 percent being recycled water into the drinking water supply system. In Israel, Australia, Southern California, Florida, and Arizona treated domestic wastewater is used for irrigation, toilet flushing and clothes washing purposes, reducing the withdrawals of scarce river or groundwaters. In Australia (particularly Sydney, Melbourne, and Perth), which has been experiencing a 10-year drought, the government has mandated that all new housing have both a potable and a nonpotable water supply (i.e., the latter consisting of the appropriated-treated recycled wastewater from the community). In many parts of the world, recycled wastewater is treated to a level that is considered relatively safe for irrigation purposes. A fit-for-purpose system requires reservoirs for both potable and nonpotable waters, at the community and/or household level. Approximately 75 percent of domestic water is used for flushing toilets, garden irrigation, and clothes washing, which means that the non-potable water reservoirs will need to be of a sufficient size to accommodate the demand. Hence, fire fighting flow, the main determinator of the size of a water
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distribution system, should be via non-potable water, leaving opportunity for a smaller, better quality drinking water distribution system.
A second opportunity is to rethink wastewater disposal. Recognizing that the human body keeps urine and fecal materials separate and that urine is approximately less than 1 percent of the output into the sewerage system, there has been interest in separating urine flow from the fecal material as it exits the body. Not only is this separation viewed as sustainable, but the collected urine (yellow water) can be used as a fertilizer for agricultural purposes. About five companies, particularly in Scandinavia and Germany, make urine-diversion toilets for domestic use, and nongovernmental organizations (NGOs) have assisted in developing urine-diversion pit latrines that are self-financing (through the sale of yellow water) in southern China, Africa, and India.
Most pharmaceuticals, including endocrine-disrupting compounds are primarily excreted via urine, and using yellow water in agriculture prevents these compounds from entering the water supply. Furthermore, utilizing natural soil microbes to degrade these endocrine disruptors to agriculture may be far more economically feasible than treating the chemicals at a water treatment facility. Soil is a more reactive location, microbiologically speaking, to break down those compounds than in water. In a pilot study, looking at the uptake of some of these compounds into plants grown hydroponically and in soil, very low levels of endocrine disruptors were detected in the plants, which means that this method can be a potentially safe alternative.
In some “ecological villages,” there has been an effort to focus, not on past water engineering marvels, such as huge dams, pipe systems, and aqueducts, but rather on how to supply sustainable water services to communities in the future. For example, the services needed in a house can be split into three types of source waters and three waste streams: black water from the toilet fecal flushings; grey water, the bulk of the water used in a household; and the yellow water, which is the urine stream. The black water could go directly to a composter or into a vacuum sewer to an energy-recovery plant. Grey water could be used for recycling or reuse either within the household or locally. The yellow water can be diverted as a fertilizer, as noted above either as a liquid for local use or as a solid precipitate for export.
A third opportunity builds on pilot programs in rural Philippines and Bhutan. Efforts have started there to create a clean-tech water supply system that only runs on solar energy. A further innovation is the use of a credit card device that can be recharged at the local city hall to activated local water dispenser in the community. In this example, the groundwater is chlorinated and distributed by gravity to dispensing areas, where people fill various containers. Although the standpipes are sources of good-quality potable water, the system can fail if it is not maintained safely by the user in the home.
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Exposure and Health
The majority of the large urban systems have pipe infrastructures that are prone to leaks. These leaks can be in the potable water infrastructure or the wastewater infrastructure, which can contaminate recreational areas, groundwater supplies, and other areas. On the water distribution side, cross-contamination/contaminant intrusions are one of the difficulties for even the “jewel” distribution systems. For example, every year in Sydney, cross-connections of non-potable are being detected in the potable water system, potentially impacting consumers. In other words, people are drinking the highly treated recycled water. While this water is treated to a level that is actually considered safe, cross-connections occur through illegal connections and are a warning to others contemplating this type of dual distribution system. A less well understood potential problem is the growth of pathogenic microbes in non-potable water systems, where higher nutrients and periods of stagnant flow may promote their growth.
WHO has developed guidelines for drinking water, recreational use, and water reuse, which are based on the risk assessment approach in Figure 3-8 and differs from the U.S. guidelines. WHO uses a health target based on some toler-
FIGURE 3-8 The World Health Organization’s (WHO’s) risk assessment approach guidelines for drinking water, recreational use, and water reuse. WHO uses a health target based on some tolerable level of risk, resulting in a risk management system that is primarily based on the Hazard Analysis Critical Control Point approach used in the food industry.
SOURCE: Fewtrell, L., and J. Bartram. 2001. Water Quality: Guidelines, Standards & Health Assessment of Risk and Risk Management for Water-Related Infectious Disease. World Health Organization. IWA Publishing. Reprinted with permission.
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able level of risk, resulting in a risk management system that is primarily based on the Hazard Analysis Critical Control Point approach used in the food industry; known now as the Water Safety Plan. On the basis of a person’s exposure, an assessment of risk is determined.
The quantitative microbial risk assessment approach uses a framework (Figure 3-9) that is based on the chemical risk assessment framework developed by the National Research Council (1994). After describing the system and identifying the hazards in the system, this approach determines the exposure from the hazards, and dose-response models characterize the risk. The risk assessment approach is an iterative process, as more data specific to the location of interest are generated, to reduce uncertainties in risk estimates, and it is necessary to confirm with the stakeholders early on that all the agents of concern have been identified. The ultimate outcome is to help better manage the system by characterizing the risk.
FIGURE 3-9 The quantitative microbial risk assessment framework is based on the chemical risk assessment framework developed by the National Research Council. This approach determines the exposure from the hazards, and dose-response models characterize the risk. The risk assessment approach is an iterative process, as more data specific to the location of interest are generated, and it is necessary to confirm with the stakeholders early on that all the agents of concern have been identified.
SOURCE: Adapted from NRC (National Research Council). 1983. Risk Assessment in the Federal Government: Managing the Process. Washington, DC: National Academy Press; NRC (National Research Council). 1994. Science and Judgment in Risk Assessment. Washington, DC: National Academy Press.
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The risk-based water guidelines have a number of ramifications, such as no longer focusing on end-point testing for specific maximum contaminant criteria. Water is treated to be “fit-for-purpose,” which is based on the quality of the raw water and the tolerable burden/dose of hazards at the point of exposures. The risk-tolerance approach still needs a benchmark to determine the health target, which the U.S. EPA does not have. Instead, the EPA has used one infection per 10,000 per year in developing the surface water treatment rule in the late 1980s and the enhanced surface water treatment rule. WHO has developed with the disability-adjusted life year (DALY) benchmark as a common metric for health effects; using 1 DALY per 1 million people per year, which is equal to approximately 1 case of cancer per 100,00 people over a lifetime of 70 years (Murray and Lopez, 1996).
Quantitative microbial risk assessments have been undertaken in Australia for large-scale system for water systems, and qualitative assessments are now standard aids in prioritizing risk management actions. They help to focus on such issues as source water protection targets, treatment performance needs, effects of integrity losses, and a systems analysis approach. For some of the pathogens of interest, the maximum tolerable concentrations are below the detection limits of the current technology based on 1 DALY per 1 million people per year benchmark. So rather than focusing on largely undetectable pathogens in drinking water, the quantitative approach has the benefit of promoting the control of hazards of interest at their upstream sources as an important strategy to managing pathogens risks.
There are trade-offs in water services. For example, how does one compare an infection of cryptosporidiosis—a self-limiting diarrhea—to developing cancer from a disinfection by-product of treating water? Chlorination is ineffective against Cryptosporidium, but ozone is effective. However, ozone generates a number of disinfection by-products, such as bromate. WHO and the EPA classify bromate as a genotoxic carcinogen because it induced tumors in rat kidney, thyroid, and mesothelium and renal cancers in mice (Havelaar et al., 2000). As a common metric, DALYs can be used to determine the right balance between controlling cryptosporidiosis and addressing problems with disinfection by-products (Table 3-1).
Guidelines
The U.S. EPA currently has the National Primary Drinking Water Standards as a guideline of the maximum contaminant levels (MCLs) for various chemicals, by-products, or biological agents. The standards also list health goals, which may be lower or higher than the MCL—most importantly, they are unenforceable. For Cryptosporidium, there is no MCL for drinking water, because it would need to be below detection.
There has been a shift away from a strategy for regulating chemicals using
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TABLE 3-1 Balancing the Risks of Drinking Water Disinfection (Point Estimates Based on Median Values)
O3 benefit for effect
Cryptosporidium
Bromate
Total
Gastro gen pop
Gastro AIDS
Renal cancer
Reduction
Morbidity
500
0.33
−0.01
Mortality
0.003
0.32
−0.006
YLD
0.50
0.01
0.00
0.51
LYL
0.02
0.23
−0.06
0.19
DALY
0.52
0.24
−0.06
0.70
NOTE: LYL = life years lost; YLD = years lived with disability.
SOURCE: Derived from Havelaar, A.H., A.E. De Hollander, et al. 2000. Balancing the risks and benefits of drinking water disinfection: Disability adjusted life-years on the scale. Environmental Health Perspectives 108(4):315-321.
an analyte-by-analyte approach. WHO used the risk management approach first in the Annapolis Protocol (WHO, 1999), for recreational waters, then in their guidance for safe recreational water (WHO, 2003), third edition of the Drinking-Water Guidelines (WHO, 2004), and Wastewater Reuse, Volumes 2 and 3 (WHO, 2006a,b). All of these guidelines make use of an approach to a water safety plan that uses hazard analysis (Figure 3-10) and in particular, identifies hazardous
FIGURE 3-10 Systemwide hazard analysis and critical control point management of water. This approach uses system analysis, from the watershed to reservoirs, treatment, distribution, and finally exposure leading to potential infection. There are a number of opportunities to identify those hazards and hazardous events as well as the critical control points.
SOURCE: Ashbolt unpublished.
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events to manage. This approach is a system analysis, from the watershed to reservoirs, treatment, distribution, and finally exposure leading to potential infection. There are a number of opportunities to identify those hazards and hazardous events as well as the critical control points and target levels for management.
The European Union’s Micro-Risk Project applied the source-to-customer Quality Management and Analysis System for 10 full-scale operational drinking water systems in Europe and one in Australia, focusing on six reference pathogens through various hazardous events. It became clear that much of the uncertainty in the estimate of infection probability came from what occurs in the distribution system. That study highlighted why there is uncertainty in detecting E. coli in distribution waters and trying to determine what it represents (e.g., sewage contamination, a bird in a reservoir, soil seepage). Figure 3-11 shows
FIGURE 3-11 Pathogen to themotolerant coliform ratios in environmental samples collected from sewage, surface water, and groundwater. Campy = Camplobacter, Crypto = Cryptosporidium, virus cult = ratios of culturable enteric virus vs. themotolerant coliforms from data pairs in which thermotolerant coliforms were dectable; virus pos = ratios of both culturable enteric viruses and enteroviruses detactable with PCR vs. detectable thermotolerant coliform concentrations; virus all = all ratios (when themotolerant coliforms were not detectable, their concentration was estimated to be half the detection limit in order to be able to calculate a ratio). Two samples in sewage and 24 samples in soil or shallow groundwater did not contain detectable concentrations of pathogens and ratios were set to 1 × 108 and 1 × 104, respectively, for the purpose of presentation in this graph only (indicated with arrows), including calculations of means and standard deviations. The number of data pairs per pathogen is indicated over the graphs.
SOURCE: Van Lieverloo, J.H., E.J. Mirjam Blokker, et al. 2007. Quantitative microbial risk assessment of distributed drinking water using faecal indicator incidence and concentrations Journal of Water and Health 5(Suppl 1):131-149. Reprinted with permission.
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the relationship between E. coli and the pathogens from different sources, be it sewage, surface water or groundwater.
With various technologies, there are various types of exposures, and the guidelines, which have been heavily focused on end-point testing, have not necessarily helped in managing the situation. Newer approaches by WHO and the EPA are moving upstream for better management of the system. However, there is a need to further reduce the uncertainties, which include technical, social, and environmental uncertainties.
Major uncertainties in providing safe drinking water have been identified by the Quality Management and Analysis System, including short-duration system failures that lead to fecal pathogens in drinking water and distribution system intrusions that are likely to overwhelm the chorine disinfectant. In the United States, a number of agents have been attributed to drinking water outbreaks. Legionella pneumophila, which has been registered only since 2001, is probably the predominant water-borne pathogen now identified by the Centers for Disease Control and Prevention. However, a number of similar opportunistic bacterial pathogens exist, including Mycobacterium avium, Burkolderia pseudomallei, Helicobacter pyloria, and Campylobacter jejuni. From a research point of view, all of these opportunistic pathogens that may grow post water treatment in distribution systems, including some novel viruses called mini viruses, grow inside amoebae that naturally colonize biofilms in water after treatment in distribution systems, particularly inside building plumbing and hot water systems.
To conclude, sustainable water services need to consider the routes of pathogen exposure, including drinking, but also inhalation. When new technologies are developed and implemented—for example, recycled waters or water fit for purpose—their risks need to be assessed. As such, there needs to be an integrative assessment approach to address health that moves beyond traditional end-point assessments and includes all types of water exposures so resources are focused on the most important issues and locations for management.
APPROACHES TO SUSTAINABLILITY: GLOBAL WATER PARTNERSHIPS
Wayne Joseph, M.Sc., Chair
Global Water Partnership—Caribbean
Access to water supplies and drinking water cannot be discussed without considering water as a resource in totality. Water availability is a function of not only rainfall, but also the size of the land mass and population. For example, a small island with a low level of rainfall and a large population would be water stressed.
The Caribbean comprises the geographic area from Trinidad in the south to the Bahamas in the north. The annual rainfall varies across the region. Costa Rica has the largest annual rainfall in the region, with an average of 132.1 inches per
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year. In general, countries that are close to Costa Rica, are located on the mainland, or are close to the mainland tend to have the largest rainfalls. For a number of countries in the region, the annual per capita freshwater availability is below 1,000 cubic meters, which is the threshold for being considered water stressed.
To replenish aquifers and surface water sources, countries are very dependent on rainfall. However, climate variability is impacting water resources in the region because of changes in rainfall patterns. High-intensity, short-duration rainfall patterns are leading to runoff and flooding. Furthermore, these intense periods are followed by longer dry periods, resulting in reduced stream flows and a reduction in reservoir storage. Other changes are noticeable, such as the greater rainfall outside the conventional catchment areas and an increase in the frequency of extreme events. For example, two 50-year floods in Guyana within a two-year period have occurred. In addition, sea level rise, seawater surges during hurricane storms, and occasional flooding, as has occurred in the Bahamas, can cause aquifer contamination of the water supply.
Governance and Economics
Often multiple ministries in governments are responsible for water, and integrated water resources management is not practiced widely in the region. The result is that the programs of the various agencies may be slightly in conflict with one another. An integrated water system has to address the needs of the various sectors. In Trinidad and Tobago, both the agriculture and the tourism industries are reliant on fresh water and are negatively impacted by changing weather patterns as a result of climate change. For example, because the agricultural infrastructure cannot adequately incorporate the changes in the rainfall patterns, there is need for new infrastructure, including dams, wells, and associated sources, and for use of more efficient irrigation technologies, such as drip feed. The region needs to develop drought-resistant crops and to learn from other countries experiencing changing rainfall patterns.
Tourism also uses a significant volume of available fresh water for arriving cruise ships and hotels and for irrigation of golf courses. These industries can easily exceed the carrying capacity of the island. The demand has outstripped the supply, since industrialization and development as a result of tourism are happening at the same time. Currently, the water supply infrastructure is inadequate to provide the service levels that are expected by customers. For example, in Trinidad and Tobago, although development is occurring at a record pace, only 26 percent of the population receives a continuous water supply. The remainder of the population receives intermittent water supply.
The International Plant Protection Convention and local studies of the region have confirmed that the Caribbean is vulnerable to climate change. The agriculture, tourism, and health sectors will definitely be affected, so there is a need to quantify the extent of the impact of climate change on these economic sectors. Such an assessment will require a commitment to research, including the location
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and the extent of sea level rise throughout the country. It can provide a vulnerability map of the areas inundated with water to plan for effects on tourism and agriculture.
Current Water Challenges and Planning for the Future
One of the largest challenges is that water is not treated as an economic good. Some countries in the Caribbean have a metering policy in place, and other countries, such as Trinidad, do not. Even when metering is in place, tariffs are relatively low. Thus the current rating structure does not penalize wastage. In order to combat these challenges, the area is starting to recognize that water needs to be recycled to reduce the demand on the potable water supplies by moving toward an integrative water management approach that focuses on conservation. One of the essential features is the inclusion of reverse-osmosis filtration technology to treat sewage to a very high-quality standard for reuse.
Furthermore, as governments discuss strategies for mitigation of climate change, water resource management needs to be planned for extreme events, not based on historical data or trends. Such a strategy will encompass the design of larger storage reservoirs to accommodate long dry spells or short periods of higher intensity rainfall. Urban catchment areas need to collect and pump runoff from the catchment area to storage reservoirs, similar to the strategies being employed in Singapore.
Another strategy for the region, which is already being employed in Trinidad, is the use of desalinated technologies to produce potable water. Trinidad’s desalination facility produces 24 million imperial gallons of water per day. It is expensive, but, for some countries, it is necessary.
Global Water Partnership
Through the development of the Global Water Partnership, the region is supporting an integrated, sustainable approach to water resources by working closely with the Caribbean Water and Wastewater Association, the United Nations Environmental Programme, the Integrated Watershed and Coastal Areas Management Program, and various nongovernmental organizations. The mission is to support countries in the sustainable management of their water resources. Currently, there are 40 partners from 16 different countries. The Global Water Partnership is committed to a participatory approach to development of water resources in the region and to treating water as a finite resource. Part of the outreach is at the ministerial level, to have top down support, although the organization believes that all stakeholders should be involved in the development of sustainable policies. Some examples of this approach include establishing a rainwater-harvesting model for poor rural communities in the Caribbean that can be easily adaptable to each island’s specific needs.