Water
Key facts
- In 2012, 89% of the world’s population had access to an improved drinking-water source, compared with 76% in 1990.
- Almost 4 billion people now get water through a piped connection; 2.3 billion access water through other improved sources including public taps, protected wells and boreholes.
- 748 million people rely on unimproved sources, including 173 million who depend on surface water.
- Globally, 1.8 billion people use a drinking-water source that is contaminated with faeces.
- Contaminated water can transmit diseases such diarrhoea, cholera, dysentery, typhoid and polio. Contaminated drinking-water is estimated to cause more than 500 000 diarrhoeal deaths each year.
- By 2025, half of the world’s population will be living in water-stressed areas.
Introduction
Safe and readily available water is important for public health, whether it is used for drinking, domestic use, food production or recreational purposes. Improved water supply and sanitation, and better management of water resources, can boost countries’ economic growth and can contribute greatly to poverty reduction.
In 2010, the UN General Assembly explicitly recognised the human right to water and sanitation. Everyone has the right to sufficient, continuous, safe, acceptable, physically accessible and affordable water for personal and domestic use.
Access to water
The Millennium Development Goal (MDG 7) on drinking-water was met globally in 2010. The target was to halve the proportion of the world’s population without sustainable access to safe water. Sub-Saharan Africa, which started with low levels of provision and saw high population growth in this period, is not on track to achieve the target by 2015. Progress has nonetheless been impressive. Since 2000, almost a quarter of the region’s population gained access to an improved source of drinking-water – that is 50 000 people a day for 12 years.
Sharp geographic, sociocultural and economic inequalities persist, not only between rural and urban areas but also in towns and cities where people living in low-income, informal or illegal settlements usually have less access to improved sources of drinking-water than other residents.
Water and health
Contaminated water and poor sanitation are linked to transmission of diseases such as cholera, diarrhoea, dysentery, hepatitis A, typhoid and polio. Inadequate or absent water and sanitation services in health-care facilities put already vulnerable patients at additional risk of infection and disease.
Inadequate management of urban, industrial and agricultural wastewater means the drinking-water of millions of people is dangerously contaminated or chemically polluted.
More than 840 000 people are estimated to die each year from diarrhoea as a result of unsafe drinking-water, sanitation and hand hygiene. But diarrhoea is largely preventable for example, the deaths of some 360 000 children aged under 5 each year could be avoided each year if these risk factors were addressed. Where water is not readily available, people may decide handwashing is not a priority, thereby adding to the likelihood of diarrhoea and other diseases.
Diarrhoea is the most widely known disease linked to contaminated food and water but there are other hazards. For example, some 200 million people are affected by schistosomiasis – an acute and chronic disease caused by parasitic worms contracted through exposure to infested water.
In many parts of the world, insects that live or breed in water carry and transmit diseases such as dengue fever. Some of these insects, known as vectors, actually breed in clean, rather than dirty or stagnant water, so water quality is not always an issue. However, it is important to cover water containers to help prevent mosquitoes and other vectors breeding in them.
Economic and social effects
When water comes from improved and more accessible sources, people spend less time and effort in physically collecting it, meaning they can be productive in other ways. It can also result in greater personal safety by reducing the need to make long or risky journeys to collect water. Better water sources also mean less expenditure on health, as people are less likely to fall ill and incur medical costs, and are better able to remain economically productive.
With children particularly at risk from water-related diseases, access to improved sources of water can result in better health and therefore better school attendance, with longer-term consequences for their lives.
Water sources
Surveys of people’s access to water and sanitation refer to “improved” or “unimproved” sources. But “improved” does not necessarily mean there are no health risks. A substantial proportion of water supplied through pipes is contaminated, especially where water supply is intermittent or treatment is inadequate. Even where the source is good, water can be contaminated while being transported or stored. Some 1.8 billion people use a drinking-water source that is contaminated with faecal matter.
Challenges
Climate change, increasing water scarcity, population growth, demographic changes and urbanization already pose challenges for water supply systems. By 2025, half of the world’s population will be living in water-stressed areas. Re-use of wastewater, to recover water, nutrients, or energy, is becoming an important strategy. Increasingly countries are using wastewater for irrigation - in developing countries this represents 7% of irrigated land. However, this practice poses health risks that need to be weighed against potential benefits of increased food production.
Options for water sources used for drinking-water and irrigation will continue to evolve, with an increasing reliance on groundwater and alternative sources, including wastewater. Climate change will lead to greater fluctuations in harvested rainwater. Management of all water resources will need to be improved to ensure provision and quality.
WHO's response
As the international authority on public health and water quality, WHO leads global efforts to prevent transmission of waterborne disease, advising governments on health-based targets and regulations.
WHO produces a series of water quality guidelines, including on drinking-water, safe use of wastewater, and safe recreational water environments. The Guidelines for Drinking-water Quality are based on managing risks, and since 2004 include the promotion of Water Safety Plans to identify and prevent risks before water is contaminated. WHO works on promoting effective risk assessment and management practices among all groups, including suppliers of drinking water, wastewater treatment companies, farmers, communities and individuals.
In early 2014, WHO launched an international scheme to evaluate household water treatment technologies that will provide independent testing and advice based on WHO criteria.
WHO is working with UNICEF on a global action plan to end preventable child deaths from pneumonia and diarrhoea by 2025. This plan also sets out several prevention and treatment targets, including achieving universal access to drinking water, in health-care facilities and homes by 2030.