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Coping with Water Scarcity

Children collecting water in Sierra Leone

Children collecting water in Sierra Leone. Photo credit: Sharon Roy, 2006.

The United Nations has declared March 22 of each year as World Water Day. The objective of World Water Day is to promote activities related to the conservation and development of water resources. This year the theme is “Coping with Water Scarcity.” (1)

Water Scarcity

Water scarcity occurs when there is an imbalance between the availability of water and the demand for water. When we hear people talking about water scarcity, we often think of drought, but this is only one of several causes. Other issues also impact the availability of fresh water, including the deterioration of ground water and surface water quality, competition for water between different segments of society (for example, between agricultural, industrial, and domestic users), and even social and financial barriers limiting access to water. (2)

While approximately three quarters of the earth is covered by water, only a small proportion of it is available as fresh water. Of the available fresh water supplies, nearly 70% is withdrawn and used for irrigation to produce food – and the demand just keeps growing.(3) Although there is currently no global scarcity of water, more and more regions of the world are chronically short of water.(2) At present, 1.1 billion people have little choice but to use potentially harmful sources of water, and 2.6 billion people – half the developing world – lack access to adequate sanitation.(4) By 2025, an estimated 1.8 billion people will be living in countries or regions with an absolute water scarcity, and two-thirds of the world population may be under stress conditions. This situation will only worsen as rapidly growing urban areas place heavy pressure on neighboring water supplies.(2)

In September 2000, the United Nations adopted eight Millennium Development Goals for promoting human development. One of the targets is to halve, by 2015, the proportion of people without sustainable access to safe drinking water and basic sanitation. However, according to the mid-term assessment of progress towards this goal, some regions, including sub-Saharan Africa will not meet their targets if current trends are confirmed.(5)

Improving Access to Safe Water and Basic Sanitation around the World

While larger scale projects, such as the construction of deep wells or piped water systems, remain important objectives of many development agencies, a shortage of time and resources will leave hundreds of millions of people without access to safe water into the foreseeable future. To help bridge the enormous gap in developing countries between populations served by existing water projects and those most in need, CDC and the Pan American Health Organization developed the Safe Water System (SWS), an adaptable and flexible intervention that employs technologies appropriate for the developing world.

SWS being used in Kenya

SWS use in Kenya. Photo credit: John Brooks, 2006.

The SWS empowers families to improve the quality of the water they drink through simple, inexpensive technologies to treat and safely store drinking water in their homes. The intervention consists of three steps:

Many studies have documented a reduced risk of diarrhea in families who treat their household drinking water by chlorination, filtration, combined chlorination and flocculation, or solar disinfection.(6) More information on household water treatment is available from CDC at Safe Water System (SWS) and from the World Health Organization (WHO) at The International Network to Promote Household Water Treatment and Safe Storage.

In many places, water provision efforts suffer from a lack of technical knowledge to effectively manage or adapt a system to a community’s changing needs. Water Plus/Agua y Mas, developed by CDC and the Andean Health Organization, is a community-based, integrative approach to improving health and quality of life through increased access to improved water, sanitation, and hygiene. This methodology includes the following elements:

Water quality testing in Bermejo, Bolivia

Water quality testing in Bermejo, Bolivia. Photo credit: Lana Corrales, 2006.

  • A Water Safety Plan, which includes an assessment of the water delivery system from catchment to consumer;
  • Appropriate interventions, which can include protection of source waters, improvements to the water delivery system, introduction of Safe Water Systems, improved sanitation, and hygiene education; and
  • Evaluation of the impact of the interventions on the health and quality of life of the consumers.

More information about Water Plus/Aqua y Mas is available at Environmental Health Office of Global Health.

Other methods to protect people from contaminated water are being employed by the Guinea Worm Eradication Program. Guinea worm disease (GWD), also called dracunculiasis, is a preventable parasitic infection that affects poor communities in remote parts of Africa that lack safe drinking water. The infection is transmitted to people who drink water containing copepods (tiny water fleas) that are infected with the larvae of the Guinea worms. Once ingested, these larvae take up to one year to grow into adult worms; the female worms then emerge from the skin anywhere on the body. Emergence of the adult female worm can be very painful, slow, and disabling and prevents people from working in their fields, tending their animals, going to school, and caring for their families.(7)

Guinea worm emerging from a foot

Guinea worm emerging from a foot. Photo credit: The Carter Center, 2007.

Currently, many organizations, including The Global 2000 program of The Carter Center, the World Health Organization (WHO), UNICEF, and CDC are helping the last nine endemic countries (all in sub-Saharan Africa) to eradicate this disease. Since the Guinea Worm Eradication Program began in 1986, the incidence of Guinea worm disease (GWD) has declined from 3.5 million cases per year in 20 endemic countries to 25,018 reported cases in 2006 from the 9 remaining endemic countries.(8) The eradication efforts make use of simple interventions for providing safe drinking water, including using cloth filters and pipe filters to strain the infected copepods from the water, applying chemicals to the water supplies to kill the larvae, and preventing infected people from entering and contaminating the water supplies as the worms emerge from their skin. Providing borehole wells and other supplies of safe drinking water in endemic villages is another important component of the eradication efforts. More information about GWD and the eradication program is available from CDC at Parasitic Disease Information – Dracunculiasis, from The Carter Center at Guinea Worm Eradication Program, and from WHO at Dracunculiasis.

Healthy Drinking Water in the United States

Advances in water quality have dramatically improved the public’s health in the United States. However, new challenges to the nation’s water quality have arisen. These include the emergence of chlorine-resistant pathogens, chemical contamination of water sources, aging infrastructure, increased recreational water contamination, cooling tower and other non-traditional water exposures, and increasing water re-use. These challenges are reflected in rising numbers of disease outbreaks associated with 1) small or individual water systems, 2) recreational water 3) building distribution systems, and 4) other uses of water. An estimated 4 to 33 million cases of gastrointestinal illness associated with public drinking water systems in the United States occur annually. However, these estimates are imprecise and do not include illness in the 45 million people served by small or individual water systems, the >60 million people swimming every year, other water exposures, or illness other than gastrointestinal illness.

water tower

Reservoir tank or "water tower." Photo credit: Public Health Image Library.

CDC has water-related activities occurring across the agency that address domestic water and public health issues from various perspectives, including the public health effects from contaminated drinking and recreational waters, waterborne disease outbreak surveillance and investigations, support for local and state health departments delivering water-related programs, and waterborne terrorism issues.

More information about healthy drinking water and CDC’s efforts in this area can be found at the following websites:

* Links to non-Federal organizations found at this site are provided solely as a service to our users. These links do not constitute an endorsement of these organizations or their programs by CDC or the Federal Government, and none should be inferred. CDC is not responsible for the content of the individual organization Web pages found at these links.


  1. United Nations Educational Scientific and Cultural Organization. 22March - World Day for Water: Coping with Water Scarcity. Available at:
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  2. UN-Water. Coping with Water Scarcity: UN-Water Thematic Initiative. August 2006. Available at:
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  3. UN-Water. World Water Day 2007 Official Brochure. Available at:
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  4. World Health Organization. Meeting the MDG Drinking Water and Sanitation Target: A Mid-Term Assessment of Progress. Available at:
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  5. World Health Organization and UNICEF. Meeting the MDG Drinking Water and Sanitation Target: The Urban and Rural Challenge of the Decade. 2006. Available at:
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  6. Clasen T, Roberts I, Rabie T, Schmidt W, Cairncross S. Interventions to improve water quality for preventing diarrhea. 2006. Cochrane Database Syst Rev 3: CD004794.
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  7. Hopkins DR, Ruiz-Tiben E, Downs P, Withers Jr. PC, Maguire JH. Dracunculiasis Eradication: The Final Inch. Am J Trop Med Hyg. 2005;73(4):669-75.
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  8. WHO Collaborating Center for Research, Training and Eradication of Dracunculiasis. Guinea Worm Wrap-Up #170. 2007. Available at:
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Division of Parasitic Diseases
Division of Foodborne, Bacterial and Mycotic Diseases (proposed)
Division of Emergency and Environmental Health Services
Division of Environmental Hazards and Health Effects
Office of Global Health NCEH/ATSDR

National Center for Infectious Diseases
National Center for Environmental Health

Content Source: Division of Parasitic Diseases, Division of Foodborne, Bacterial and Mycotic Diseases (proposed), and Office of Global Health NCEH/ATSDR
Page last modified: March 19, 2007