Water issues in developing countries
Access- Availability & Challenges
Approximately 80% of all illnesses in developing countries are caused by poor water and sanitation conditions. It is common for women and girls to have to walk several kilometers every day to fetch water for their families. Once filled, water jugs can weigh as much as 20 kg (44 lbs).[1]
In the last century, water use has greatly outpaced the rate of population growth: people are using more water than ever before. By 2025, up to 1.8 billion people could face water scarcity.[2] Water scarcity can take two forms: physical water scarcity, or low quantity of water, and economic water scarcity, or low quality of water.
Physical water scarcity
This term typically applies to dry, arid regions where fresh water naturally occurs in low quantities. This is being greatly exacerbated by anthropogenic activities that take surface and ground water faster than the environment can replenish it. Regions most affected by this type of water scarcity are Mexico, Northern and Southern Africa, the Middle East, India, and Northern China.[1]
Economic water scarcity
Economic water scarcity applies to areas or cultures that lack the fiscal resources and/or human capacity to invest in water sources and meet the local demand. Water is often only available to those who can pay for it or those in political power; leaving millions of the world's poorest without access. Regions most affected by this type of scarcity are portions of Central and South America, Central Africa, India, and South East Asia.[1] It is important to highlight the distinction between these two forms of scarcity: water can be physically available, but the resources are not available to improve it and distribute it to those who need it.
Also see the Food and Agriculture Organization of the United Nations' map illustrating the 'Areas of Physical and Economic Water Scarcity' throughout the world.
Case Studies
India
India's growing population is putting a strain on the country's water resources. The country is classified as "water stressed" and a water availability of 1,000-1,700 m3/person/year.[3] According to UNICEF, in 2008 88% of the population had access and was using improved drinking water sources.[4] "Improved drinking water source" is an ambiguous term, ranging in meaning from fully treated and 24-hour availability to merely being piped through a city a sporadically available.[5] This is in part due to large inefficiencies in the water infrastructure in which up to 40% of water leaks out.[5]
In the same 2008 UNICEF report, only 31% of the population had access and used improved sanitation facilities.[4] Open sewers are common place in urban areas.[5] A little more than half of the 16 million residents of New Delhi, the capital city, have access to this service.[5] Every day, 950 million gallons of sewage flows from New Delhi into the Yamuna River with any significant forms of treatment.[5] This river bubbles with methane and was found to have a fecal coliform count 10,000 time the safe limit for bathing.[5]
Due to surface water contamination due to lack of sewage treatment and industrial discharge, groundwater is becoming increasingly dependent on and exploited in many regions of India.[6] This process is being expedited by heavily subsidized energy costs for agriculture practices;[6] which make up roughly 80% of India's water resource demand.[7]
Kenya
Kenya, a country of 36.6 million, struggles with a staggering population growth rate of 2.6% per year (by comparison, the US population growth rate is 0.899% and the population growth rate in India is 1.31%).[8] This high population growth rate has pushed Kenya's natural resources to the brink of destruction. Much of the country suffers from a severe arid climate, with only scarce few areas enjoying rain and access to water resources. Deforestation and soil degradation have made the available surface water typically highly polluted and difficult to retain. The government has been unable to afford to develop water treatment or distribution systems, leaving the vast majority of the country without access to water. This has also exacerbated gender politics, as 74% of women must spend an average of 8 hours per day securing water for their families.[9] The growing population and stagnant economy has exacerbated urban, suburban, and rural poverty—exacerbated by lack of access to clean drinking water which leaves much of the non-elite population suffering from disease and parasites. This has effectively crippled Kenya's human capital.[10] Private water companies have taken up the slack from Kenya's government among the wealthy, but the Kenyan government prevents them from moving into the poverty-stricken areas of the country in order to stop profiteering off the poor.[9] Unfortunately, since Kenya's government also refuses to provide services, this leaves the disenfranchised with no options at all for obtaining clean water—or any water.
Bangladesh
Historically, water sources in Bangladesh came from surface water contaminated with bacteria. As a result of drinking infected water, infants and children suffered from acute gastrointestinal disease, causing significant burden of mortality.[11] During the 1970s, UNICEF worked with the Department of Public Health Engineering to install tube-wells, which drew water from underground aquifers, to provide a presumably safe source of water for the nation. The wells consist of tubes 5 cm in diameter that were inserted less than 200 m into the ground, and capped with an iron or steel hand pump. At that time, standard water testing procedures did not include arsenic testing.[11] This lack of precaution led to one of the largest mass poisoning of a population twenty years later because the ground water used for drinking is naturally contaminated with arsenic.[12] Because arsenic has no taste, no smell, and no color, its long term health risks can be harder for the inhabitants to grasp compared to the immediate threats caused by diarrhoea. Nonetheless, intervention measures such as awareness programs and painting tube-wells red if the water is above the government limit of 50 ppb arsenic (green otherwise) have seen success. As of 2010, 80% of Bangladeshis recognize arsenic as a problem.[13] Available options for providing safe drinking water include deep wells, traditional dug wells, treatment of surface water, and rainwater harvesting.[14] Between 2000 and 2009, more than 160,000 safe water devices have been installed in arsenic-affected regions of Bangladesh.[13]
Water quality
Even after accounting for physical water availability or access, water quality could further reduce the amount of usable water available to a developing country for human consumption, sanitation, agriculture and industrial purposes, in addition to various ecosystem services. The level of water quality depends on its intended purpose: Water that could be unfit for human consumption could be still usable in industrial or agriculture applications. Yet parts of the world are experiencing extensive deterioration of water quality, in some cases even rendering the water unfit for agricultural or even industrial use. For example, in China, 54% of the Hai River basin surface water is so polluted that it is considered un-usable.[15]
Development indicators tend to focus on access and availability of ‘safe water’, which the World Bank defines as ‘treated surface water and untreated but uncontaminated groundwater.’ Safe water is crucial not only for human health (on average,a human needs 20 litres of safe water for his daily ‘metabolic, hygienic and domestic needs’)[16] but also for economic development and environmental health. Yet, more than 1/3 of the world cannot drink their local water supply without additional treatment.[17]
Safe water one of the eight Millennium Development Goals: Target 7.C; "Halve, by 2015, the proportion of the population without sustainable access to safe drinking water and basic sanitation",focused on increasing access to an ‘improved water source’ and to ‘improved sanitation’. Yet even having access to an ‘improved water source’ does not guarantee the water's quality, as it could lack proper treatment, become contaminated during transport or even home storage.[17] A study found that estimates of safe water, if accounting for water quality, could be dramatically reduce the proportion of a population with access to safe water, especially if the water sources were poorly maintained.[18]
Issues
Water quality is affected both by natural processes and ecosystem characteristics but also the result of human activities, including industry, domestic and agricultural uses of water.[19]
Physical contaminants of concern can reduce waters quality through the world. Specific contaminants of concern include unsafe levels and harmful varieties of microbiological and pollutants and chemical contaminants, including:
- metals (e.g. iron)[19]
- organic matter
- arsenic
- salts
- fluoride
- viruses
- bacteria
- protozoa
- parasites[15][17]
UNICEF also notes that various non-harmful physical qualities of water quality (color, taste and smell) could also render water to be perceived as poor quality and deemed un-usable by its intended users.[20]
These contaminants could come from point and non-point sources, along with naturally occurring sources, such as: natural processes (e.g. from geology, hydrology or weather)[19] industrial waste [19] domestic human waste (e.g. fecal matter)[19] agriculture (e.g. pesticide runoff)[19] pharmaceuticals.[21]
Unsafe water, along with low sanitation and hygiene represent the leading cause of death in developing countries.[19] These contaminants can lead to many various debilitating and deadly water-borne diseases, such as fever, cholera, dysentery, diarrhea and others.[17] UNICEF cites fecal contamination and high levels of naturally occurring arsenic and fluoride as two of the world's major water quality concerns. Worldwide, contaminated water leads to 4,000 diarrhea deaths a day in children under 5.[22] In Bangladesh, an estimated 1.4 million tube wells have unsafe levels of naturally occurring arsenic[23] potentially leading to arsenic poisoning.
Challenges to Water Quality
Challenges to water quality stem not only from the physical contaminants themselves but also from the sheer volume of contaminants that can overwhelm an area's infrastructure or resources to treat and remove the contaminants. Human cultural and cultural norms, in addition to governance structures, can also contribute to scenarios that further reduce the quality of available water. The absence or low enforcement of the following policy and market mechanisms in developing countries can also be detrimental to improving water quality.[24]
Water quality in developing countries is often hampered by lack of or limited enforcement of:
- emission standards
- water quality standards
- chemical controls
- non-point source controls (e.g. agricultural runoff)
- market based incentives for pollution control/water treatment
- follow-up and legal enforcement
- integration with other related concerns (solid waste management)
- trans-boundary regulation on shared water bodies
- environmental agency capacity (due to resources or lack of political will)
- understanding/awareness of issues and laws [24]
To illustrate the sheer challenge of improving water quality: in India, 80% of the health issues come from waterborne diseases.[25] Part of this challenge includes addressing the pollution of the Ganges (Ganga) river, which is home to about 400 million people.[26] The river receives about over 1.3 billion litres of domestic waste, along with 260 million litres of industrial waste, run off from 6 million tons of fertilizers and 9,000 tons of pesticides used in agriculture, thousands of animal carcasses and several hundred human corpses released into the river every day for spiritual rebirth. Two-thirds of this waste is released into the river untreated.[26]
Beyond human health and ecosystem health, water quality is important for various industries (such as power generation, metals, mining, and petroleum) which require high-quality water to operate. Less high quality water (either through contamination or physical water scarcity) could impact and limit the choices of technology available to developing countries. Reductions in water quality have the dual effect of not only increase the water stress to industrial companies in these areas but typically also apply increasing the pressure to improve the quality of the industrial wastewater.[15]
However, gaps in wastewater treatment (the amount of wastewater to be treated is greater than the amount that is actually treated) represent the most significant contribution to water pollution and water quality deterioration. In the majority of the developing world, most of the collected wastewater is returned to surface waters directly without treatment, reducing the water's quality.[27] In China, only 38% of China's urban wastewater is treated and although 91% of China's industrial waste water is treated, it still releases extensive toxins into the water supply.[15]
The amount of wastewater treatment possible can also be compromised by the networks required to bring the wastewater to the treatment plants. It is estimated that 15% of China's wastewater treatment facilities are not being used to capacity due to a limited pipe network to collect and transport wastewater. In São Paulo, Brazil, a lack of sanitation infrastructure results in the pollution of the majority of its water supply and forces the city to import over 50% of its water from outside watersheds. Polluted water increases a developing country's operating costs, as lower quality water is more expensive to treat. In Brazil, polluted water from the Guarapiranga Reservoir costs $0.43 per m3 to treat to usable quality, while water from the compared to only $0.10 per m3 for water coming from the Cantareira Mountains.[15]
Improving water resources
Improving: access
In 2011 the World Health Organization revised its Guidelines for Drinking-water Quality. This document, written for an audience of water and/or health regulators and policy-makers, is intended to aid in the development of national drinking water quality standards. The guidelines include health based targets, water safety plans, surveillance, and supporting information regarding the microbial, chemical, radiological, and acceptability aspects of common drinking water contaminants. In addition, the document offers guidance regarding the application of the drinking water quality guidelines in specific circumstances, including large buildings, emergencies and disasters, travelers, desalination systems, planes and ships, packaged drinking water, and food production.[28]
According to the WHO, "The most effective means of consistently ensuring the safety of a drinking-water supply is through the use of a comprehensive risk assessment and risk management approach that encompasses all steps in water supply from catchment to consumer. In these Guidelines, such approaches are called water safety plans (WSPs)". A WSP is a plan that will ensure the safety and acceptability of a drinking-water supply. The Water Safety Plan Manual, published in 2009 by the WHO and the International Water Association, offers guidance to water utilities (or similar entities) as they develop WSPs. This manual provides information to help water utilities to: assess their water system, develop monitoring systems and procedures, manage and community their plan, carry out periodic review of the WSP, and to review the WSP following an incident. The WSP manual also includes three case studies drawn from WSP initiatives in three countries/regions.[29]
Innovations
AQUAtap Community Drinking Water Stations
Quest Water Solutions’ AQUAtap Drinking Water Station is a simple system that uses solar power to purify contaminated groundwater, brackish water, or sea water into safe drinking water. The systems are powered by photovoltaic panels. Each Drinking Water Station is fully autonomous and can purify water at a rate of up to 20,000 litres per day without any existing infrastructure. They are also modular, so can be scaled for increased water purification. In addition, the system includes a distribution system.[30]
In 2012, Quest Water Solutions started construction of an AQUAtap Drinking Water System in Bom Jesus, an Angolan village 50 kilometers east of Luanda, the capital of Angola. The 500 residents of Bom Jesus currently rely on a dirty river for drinking water. The clean drinking water produced by the AQUAtap will be available to villagers at no cost to the villagers.[31]
HydroPack
The HydroPack, developed by Hydration Technology Innovations (HTI), is a one-time use, self hydrating, emergency hydration pouch. Victims of natural disasters often struggle to find clean drinking water. Water sources and drinking water supplies are often contaminated during a disaster; victims often suffer from water borne illnesses. The HydroPack is a 4-inch by 6-inch pouch filled with electrolytes and nutrients. When in contact with water, the HydroPack swells to create a healthy drink in 10 to 12 hours. "It doesn’t matter what the quality of water is like", says Keith Lampi, vice president and chief operating officer for HTI. "There just needs to be a source of water, even dirty or brackish water, and we can supply clean drinks at the initial stages of a disaster using the HydroPacks."[32]
The HydroPack is a 12 fluid ounce (355 millilitre) pouch with two compartments that are separated by a membrane. One side of the pouch includes a sports drink syrup. The user places the pack in a water source for 10 to 12 hours. During that time untreated water diffuses across the membrane and dilutes the sports drink syrup. The HydroPack uses Forward Osmosis, a natural equilibrium process that rejects even the harshest of contaminants. The technology does not clog and can be used in very turbid water. The pouch includes a straw and the resulting nutrient drink is very palatable. According to HTI, "HTI's products are not meant to displace other bulk water strategies such as ROWPUs, municipal water systems, or shipboard desalination and bottling. Instead, they should play a very critical role in the early phase of disaster relief until other production and distribution strategies can be put in place." This technology also reduces the weight of aide materials needed to be transported after a disaster. One pallet of 94,500 HydroPacks weighs 8,325 pounds (3,785 kg) and will produce 12,482 gallons (47,250 litres) of clean drink. This equates to about a 92% reduction in weight compared to bottled water. HydroPack were distributed to earthquake survivors in the tent city of Carrefour in Haiti in 2010.[33]
Wello
Wello, a social venture, developed the WaterWheel to improve global access to water. The WaterWheel is a non-mechanical wheel enabling one person to transport 25 gallons (90 litres) of water, enough water for one family, in a single trip. A WaterWheel user can put up to 200 pounds (90 kg) of water in the "wheel", a broad drum with round edges and a steel handle, transforming the water to an effective weight of approximately 22 pounds (10 kg). The design allows for easy maneuvering over different terrains, inclines, and corners. By reducing the number of daily trips needed to collect water, the WaterWheel allows women and children in developing countries to devote more time and energy to educational and economic activities. In addition, the WaterWheel is a sustainable solution for water transportation. It does not require any energy or other supplies in order to operate. It also does not require repairs over its 10-15 year life.[34]
Global programs
UN Water
In 2003, the United Nations High Level Committee on Programmes created UN-Water, an inter-agency mechanism, "to add value to UN initiatives by fostering greater co-operation and information-sharing among existing UN agencies and outside partners." UN-Water publishes communication materials for decision-makers that work directly with water issues and provides a platform for discussions regarding global water management. They also sponsor World Water Day (http://www.unwater.org/worldwaterday/index.html) on March 22 to focus attention on the importance of freshwater and sustainable freshwater management.[35]
The Water Project
The Water Project, Inc is a non-profit organization that develops and implements sustainable water projects in Kenya, Rwanda, Sierra Leone, Sudan, and Uganda. The Water Project has funded or completed over 250 projects that have helped over 125,000 people improve their access to clean water and sanitation.[36]
ACP-EU Water Facility
Established in 2004, the ACP-EU Water Facility received money from the European Development Fund to sponsor projects that improve water quality and sanitation and improve water management governance in African, Caribbean, and Pacific (ACP) countries.[37]
Improving Water Quality
Despite the clear benefits of improving water sources (a WHO study showed a potential economic benefit of $3–34 USD for every $1 USD invested), aid for water improvements have declined from 1998 to 2008 and generally is less than is needed to meet the MDG targets. In addition to increasing funding resources towards water quality, many development plans stress the importance of improving policy, market and governance structures to implement, monitor and enforce water quality improvements.[38]
Because of the range of pollution sources throughout the world and variable social, environmental and economic systems to address and support improved water quality, it is important to note that there is no ‘one size fits all’ solution to water quality. Various responses to improving water quality have emerged throughout the world and include:
Contaminant Reduction through Policy & Market Improvements
Reducing the amount of pollution emitted from both point and non-point represents a direct method to address the source of water quality challenges. Pollution reduction represents a more direct and low-cost method to improve water quality, compared to costly and extensive wastewater treatment improvements.[27]
Various policy measures and infrastructure systems could help limit and reduce water pollution in developing countries. These include:
- Improved management, enforcement and regulation for pre-treatment of industrial and agricultural waste, including charges for pollution[24]
- Policies to reduce agricultural run-off or subsidies to improve the quality and reduce the quantity needed of water polluting agricultural inputs (e.g. fertilizers)[19]
- Limiting water abstraction during critical low flow periods to limit the concentration of pollutants[19]
- Strong and consistent political leadership on water[24]
- Land planning (e.g. locating industrial sites outside the city) [24]
Water treatment options
For more information on Industrial Scale Treatment options:
Point of Use & Small Scale Treatment: For human consumption, various innovations and solutions (both high and low-technology based) exist throughout the developing world to treat water at the ‘point of use’ (PoU) and have been shown to an effective solution to addressing poor quality water supplies. Studies have shown that PoU treatment to reduce diaherrea mortality in children under 5 by 29% However, home water treatment solutions may not be widely considered in development strategies, as they are not recognized under the water supply indicator in the United Nations' Millennium Development Goals . Additionally, various challenges may reduce the effectiveness of home treatment solutions- such as low education, low-dedication to repair and replacement (especially if the treatment was initially free, did not meet expectations or was time intensive), or local repair services or parts are unavailable.[17]
- Current PoU & Small Scale Treatment technologies include:
- Watermaker®
- Tulip Siphon Filter
- Ceramic Water Purifier
- Water4Life Filter
- Biosand Filter
- Kanchan™ Arsenic Filter (KAF)
- AquaEst Plation® Floats
- AquaEst RainPC®
- NaDCC, also known as sodium dichloroisocyanurate
- Boiling water
- Solar disinfection (SODIS)
- LifeStraw®
- Pureit
- PUR Purifier of Water™
- Chlorine
- Jal-TARA
- Naiade
- Filter of Hope
Recycling/Re-Use:
Utilizing wastewater from one processes to be used another in another process where lower-quality water is acceptable is one way to reduce the amount of wastewater pollution and simultaneously increase water supplies. Recycling and reuse techniques can include the reuse and treatment of wastewater water from industrial plant wastewater or treated service water (from mining) for use in lower quality uses. Similarly, wastewater re-use in commercial buildings (e.g. in toilets) and use of treated municipal wastewater (e.g. for industrial cooling).[15]
Improving the quality and quantity of water are tightly linked. – for example, in São Paulo, an assessment determined that industry could save significant amounts through reducing waste and recycling its water. Gray water uses alone could add 80 million m3 in new water to the city's supply.
Removal of invasive alien plants (IAP):
Invasive plants can reduce the natural ecosystem balances, potentially increasing erosion and contributing to siltation of dams and estuaries, reducing water quality. This low-cost measure is one way to improve an area's water quality.[15]
See also
References
- 1 2 3 "The Lack of clean water: Root cause of many problems". 18 March 2012.
- ↑ "Hot Issues: water scarcity". 19 March 2012.
- ↑ "Vital Water Index". Retrieved 24 March 2012.
- 1 2 "India". Retrieved 23 March 2012.
- 1 2 3 4 5 6 "In Teeming India, Water Crisis Means Dry Pipes and Foul Sludge". Retrieved 23 March 2012.
- 1 2 "India Digs Deeper, but Wells are Drying Up". Retrieved 23 March 2012.
- ↑ "Key Water Indicator Portal-Water Statistics". Retrieved 23 March 2012.
- ↑ "Population Growth Rate". Retrieved 28 March 2012.
- 1 2 "Kenya". Retrieved 28 March 2012.
- ↑ "Poverty Reduction". 28 March 2012.
- 1 2 Smith AH, Lingas EO, Rahman M. "Contamination of drinking-water by arsenic in Bangladesh: a public health emergency." Bulletin of the World Health Organization. 2000, 78-87.
- ↑ Khan AW et al. "Arsenic contamination in groundwater and its effect on human health with particular reference to Bangladesh." Journal of Preventive and Social Medicine. 1997. 16, 65-73.
- 1 2 http://www.unicef.org/bangladesh/Arsenic_Mitigation_in_Bangladesh.pdf
- ↑ Das NK, Sengupta SR. "Arsenicosis: Diagnosis and treatment." Seminar: Chronic Arsenicosis in India. 2008. 74, 571-581.
- 1 2 3 4 5 6 7 The Barilla Group, The Coca-Cola Company, The International Finance Corporation, McKinsey & Company, Nestlé S.A., New Holland Agriculture, SABMiller plc, Standard Chartered Bank, and Syngenta AG. "Charting Our Water Future | Economic frameworks to inform decision-making" (PDF).
- ↑ World Bank. "Access to Safe Water (continued)".
- 1 2 3 4 5 Bouman, Dick, Novalia, Wikke, Willemsen, Peter Hiemstra, Jannie Willemsen (2010). Smart disinfection solutions : examples of small-scale disinfection products for safe drinking water. Amsterdam: KIT Publishers. ISBN 978-9460221019.
- ↑ Rob ES Bain, Stephen W Gundry, Jim A Wright, Hong Yang, Steve Pedley & Jamie K Bartram (2012). Accounting for water quality in monitoring access to safe drinking-water as part of the Millennium Development Goals: lessons from five countries. Bulletin of the World Health Organization.
- 1 2 3 4 5 6 7 8 9 Abbaspour, Somaya (2011). "Water Quality in Developing Countries, South Asia, South Africa, Water Quality Management and Activities that Cause Water Pollution" (PDF). International Proceedings of Chemical, Biological and Environmental Engineering. Singapore: IACSIT Press. 15.
- ↑ UNICEF. "WATER QUALITY ASSESSMENT AND MONITORING" (PDF). Technical Bulletin No.6. United Nations Children Fund (UNICEF), Supply Division.
- ↑ Lubick, Naomi. "Drug companies accused of polluting water in India". oneworld.net.
- ↑ UNICEF. "Water, Sanitation and Hygiene". UNICEF.
- ↑ UNICEF (12 October 2008). "Arsenic Mitigation in Bangladesh" (PDF).
- 1 2 3 4 5 Islam, Mohammmed Nasimul (8 September 2010). "Challenges for Sustainable Water Quality Improvement in Developing Countries" (PDF). International Water Week, Stockholm Sweden.
- ↑ Wohl, Ellen. "Special Essay: The Ganga – Eternally pure?". Global Water Forum.
- 1 2 McDermott, Mat. "World Bank Approves $1 Billion For Ganges River Cleanup". Treehugger.
- 1 2 MARKANDYA, ANIL (March 2004). "WATER QUALITY ISSUES IN DEVELOPING COUNTRIES" (PDF).
- ↑ "Guidelines for Drinking Water Quality" (PDF). World Health Organization. Retrieved 26 March 2012.
- ↑ "Water Safety Plan Manual: Step-by-step risk management for drinking water suppliers" (PDF). World Health Organization and International Water Association. Retrieved 26 March 2012.
- ↑ "Water Station utilizing Ultrafiltration (UF) system QWB-002, Product Spec Sheet" (PDF). Quest Water Solutions, Inc. Retrieved 26 March 2012.
- ↑ "Angola: Solar Panels Turning Dirty Water Clean". africanbrains.net. Retrieved 26 March 2012.
- ↑ "HydroPack: Help is on the way". Eastman Innovation Lab. Retrieved 26 March 2012.
- ↑ "Humanitarian Water". HTI Water Divisions. Retrieved 26 March 2012.
- ↑ "Water is Heavy". Wello. Retrieved 26 March 2012.
- ↑ "Discover UN-Water". United Nations. Retrieved 26 March 2012.
- ↑ "The Water Project". The Water Project. Retrieved 26 March 2012.
- ↑ "ACP-EU Water Facility". EUROPEAID. Retrieved 26 March 2012.
- ↑ GLAAS 2010: UN-Water Global Annual Assessment of Sanitation and Drink-Water. World Health Organization, UN-Water. 2010. ISBN 978 92 4 159935 1.