Health and freshwater

Posted: 26 March 2008

Of the 6.7 billion people on earth today, about 1.2 billion people lack access to potable freshwater and 2.6 billion do not have access to adequate sanitation facilities.

Despite considerable efforts to improve access to clean water and sanitation in the 1990s, when some 800 million people received improved supplies, this barely kept up with the increase in population. According to the United Nations 2000 Assessment, by the end of the 1990s there were as many people without access to these services as at the beginning, and coverage in urban areas had fallen.

Click here for graph showing water supply in urban and rural areas.

Population growth in poor countries accounts for much of this increase. However, another factor was the tremendous increase in urban populations. With massive in-migration over the decade of the 1990s, and since, the population in many developing country cities exploded. On average, developing cities has had to cope with an influx of some 60 million new arrivals every year from the countryside.

Growth rates in some cities, such as Lagos, Bangkok, Manila, Dakar, and Dar es Salaam exceeded 5 per cent per year. Such rapid and unplanned growth pushed urban services and infrastructure to the breaking point. Many migrants ended up in squatter settlements and slums, lacking electricity, water and sanitation services.

Water and Sanitation

The charts of drinking water and sanitation coverage in Figures 1 and 2 remind us of the the progress that was made from 1990 to 2002. They show also that too many people in the world still live in squalid, demeaning conditions that rob them of dignity and the means to escape from poverty.

Figure 1: Population with access to improved water supply (% of total) by region and global, 1990 and 2002

Improved sanitation 1990-2002
Note: data for Europe not availableSource: GEO Year book 2004/5, compiled from WHO/UNICEF 2004

Figure 2: Population with access to improved sanitation (% of total) by region and global, 1990 and 2002

Improved water coverage 1990-2002
Note: data for Europe not availableSource: GEO Year book 2004/5, compiled from WHO/UNICEF 2004

In 2002, there were 2.6 billion people without even the most basic sanitation facilities. Providing improved sanitation for an additional 1.8 billion from 2002 to 2015 would achieve the MDG target to halve the proportion unserved by 2015. But, because of rising population, there will still be 1.8 billion people having to cope with unhygienic sanitation facilities at that time.

The population benefiting from improved sanitation went up by 87 million a year from 1990 to 2002. An increase to 138 million a year from 2002 to 2015 is needed if the MDG sanitation target is to be met - a 58 per cent acceleration. Sub-Saharan Africa will need almost to double the annual numbers of additional people served with drinking water and quadruplicate the additional numbers served with basic sanitation if the MDG target is to be reached. So, reaching the target means going faster and investing considerably more.That is being recognized by the world community in political proclamations and in increased commitments to the sector in some of the poorest countries. There is a strong case to do even more.

Lack of drinking water and sanitation kills about 4500 children a day and sentences their siblings, parents and neighbours to sickness, squalor and enduring poverty. Improvements bring immediate and lasting benefits in health, dignity, education, productivity and income generation (Water for Life, WHO/UNICEF 2005).

Water coverage

The good news - gains in all regions since 1990 - is counterbalanced by the fact that 1.2 billion people were still using water from unimproved sources in 2006. In sub-Saharan Africa, over 60 per cent of the population is still underserved. Of the 1.2 billion people using water from unimproved sources, nearly two thirds live in Asia. The number of people without improved water sources in China alone is equal to the number of underserved in all of Africa. The lowest drinking water coverage levels are found in sub-Saharan Africa and in Oceania. In contrast, several regions, including Northern Africa, Latin America and the Caribbean, and Western Asia, have achieved coverage levels of close to 90 per cent or more.

Population growth is a significant factor in the ability of countries, particularly low-income countries, to increase the coverage of drinking water. For example, just to maintain its 1990 coverage level of 74 per cent, Peru would have had to ensure drinking water services to more than 350,000 people a year, on average, over the period 1990 to 2002. In fact, it provided water to more than 480,000 people a year, raising coverage from 74 per cent to 81 per cent.

On a global level, the number of people using improved water sources has increased by more than 90 million people a year since 1990. But because of population growth, the absolute number of people without coverage has only decreased by about 10 million people a year (WHO/UNICEF 2004 report, Meeting the MDG drinking water and sanitation target Goals).

Water-related diseases

Water-related diseases are a growing human tragedy, killing more than 5 million people each year - 10 times the number killed in wars. About 2.3 billion people suffer from diseases linked to dirty water (UN World Water Development Report 2003). The World Health Organisation says, however, that "Every year more than 2.2 million people from developing countries die from diseases associated with the lack of access to safe drinking water and inadequate sanitation. (Global Water Supply and Sanitation Assessment 2000 Report, WHO).

Child being treated for Cholera, Bangladesh. Photo: Medicins Sans Frontieres
Child being treated for Cholera, Bangladesh. Photo: Medicins Sans Frontieres
A child being treated on a cholera cot at a clinic in Bangladesh.© Medecins Sans Frontiers/Doctors Without Borders
Some 60 per cent of all infant mortality worldwide is linked to infectious and parasitic diseases, most of them water-related. In Bangladesh, for instance, an estimated three-quarters of all diseases are related to unsafe water and inadequate sanitation facilities. In Pakistan, one quarter of all people attending hospitals are ill from water-related diseases.

Adverse human health effects from water can be divided into four main categories:

  • Water-borne diseases: Those caused by water that has been contaminated by human, animal, or chemical wastes;
  • Water-based diseases: Those caused by aquatic organisms that spend part of their life cycle in the water and another part as parasites of animals;
  • Water-related vector diseases: Those transmitted by vectors, such as mosquitoes and tsetse flies, that breed or live in or near polluted and unpolluted water; and
  • Water-scarce diseases: Those diseases that thrive in conditions where freshwater is scarce and sanitation poor, such as trachoma and tuberculosis.

Water-borne diseases

Water-borne diseases include cholera, typhoid, shigella, polio, meningitis, hepatitis A and E and diarrhoea, among others. These are dirty water diseases. Most of them can be prevented if water is treated before use.

Here are some examples of dirty water diseases:

  • Diarrhoeal disease, a major health problem throughout the world, is epidemic in countries where sewage treatment is inadequate. An estimated 4 billion cases of diarrhoeal disease occur every year, resulting in 3-4 million deaths, mostly among children.
  • Raw sewage water used on vegetable fields caused outbreaks of cholera in Chile and Peru.
  • In over 150 countries, nitrates from fertilizers have seeped into water wells, fouling drinking water.
  • In Europe and Russia, the health of some 500 million people is at risk from water pollution. In northern Russia, half a million people living on the Kola Peninsula drink water contaminated with heavy metals.

Water-based diseases

Water-based diseases include guinea worm, paragonimiasis, clonorchiasis and schistosomiasis. These diseases are caused by a variety of flukes, tapeworms, roundworms and tissue nematodes, often referred to as helminths, that infect humans. Although these diseases are not usually fatal they prevent people from living normal lives and impair their ability to work.

The prevalence of water-based diseases often increases when dams are constructed, because stagnant water behind dams is ideal for snails, the intermediary host for many types of worms. For instance, the Akosombo Dam, on Volta Lake in Ghana and the Aswan High Dam on the Nile in Egypt have resulted in huge increases of schistosomiasis in these areas.

Water-related vector diseases

Millions of people suffer from infections transmitted by vectors, such as mosquitoes and flies. Such vectors infect humans with malaria, yellow fever, dengue fever, sleeping sickness and filariasis. Malaria, the most widespread, is endemic in 100 developing countries, putting some 2 billion people at risk. In sub-Saharan Africa alone, malaria costs and estimated $1.7 billion a year in treatment and lost productivity.

The incidence of these diseases appears to be increasing. There are many reasons: people are developing resistance to antimalarial drugs; mosquitoes are developing resistance to DDT, the major insecticide used; environmental changes are creating new breeding sites; and migration, climate change, and creation of new habitats mean that fewer people build up natural immunity to these diseases.

Water-scarce diseases

These diseases are transmitted when there is too little fresh water available for sanitation and washing hands. These diseases are becoming rampant throughout the world. They can be controlled easily through better hygiene, but adequate supplies of clean freshwater must be available.

See the following articles on freshwater and health:More water, better healthArsenic on tapSelf-help sewers save lives

Sources:Water - A Shared Responsibility, UNESCO, 2006.Global Environmental Outlook, GEO 4 (UNEP, Nairobi, 2007).