Water, health and ecosystems

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Directories of resources

Water, health and ecosystem linkages

Most of the earth's surface is covered by water, and most of the human body is composed of water – two facts illustrating the critical linkages between water, health and ecosystems.

To the right is a general directory of web-accessible resources focusing on linkages between health and healthy freshwater ecosystems. See Section 9 of the directory for links to major web-based meta-networks and meta-data bases, sponsored by WHO, UNEP, and other UN institutions, and section 10 for selected links sponsored by development agencies, academic/research institutes, and civil society.

Health and Environment in Integrated Coastal Zone Management

More than one-third of the world's population lives around coastal ecosystems - a special focus of the web-accessible directory link below. See Section 9 for links to WHO/UNEP portals and Section 10 for links to other organizations, e.g. development agencies, academic/research institutions and civil society.

Policy brief – water, health and ecosystems: the linkages

Global freshwater consumption rose six-fold between 1900 and 1995 – at more than twice the rate of population growth (1). Yet for many of the world’s poor, one of the greatest environmental threats to health remains lack of access to safe water and sanitation. Over 1 billion people globally lack access to safe drinking-water supplies, while 2.6 billion lack adequate sanitation; diseases related to unsafe water, sanitation and hygiene result in an estimated 1.7 million deaths every year (2).

Poor access to sufficient quantities of water also can be a key factor in water-related disease, and is closely related to ecosystem conditions. About one-third of the world's population lives in countries with moderate to high water stress, and problems of water scarcity are increasing, partly due to ecosystem depletion and contamination. Two out of every three persons on the globe may be living in water-stressed conditions by the year 2025, if present global consumption patterns continue (1).

Water ecosystems both replenish and purify water resources essential to human health and well-being. But the sustainability of many such ecosystems has been impacted by development and land use changes involving: elimination of marshes and wetlands; the diversion of surface water or alteration of flows; increased exploitation of underground aquifers; and contamination of water by waste and discharges from industry and transport, as well as from household and human waste.

The absolute quantity and the diversity of pollutants reaching freshwater systems have increased since the 1970s. These include not only biological contaminants, e.g. microorganisms responsible for traditional water-borne diseases, but also heavy metals and synthetic chemicals, including fertilizers and pesticides (1). Depending on the type of contaminent and degree of exposure, acute or chronic health impacts may result, along with impacts on the environment.

Action on solutions

An ecosystem approach: Natural ecosystems have intricate and resilient mechanisms that filter and replenish freshwater resources and sustain marine environments. Although human technologies may enhance or replicate these mechanisms in some settings, protection of the natural watershed also is critical. An 'ecosystem approach' recognizes and ascribes value, including economic value, to the 'services' natural ecosystems provide in terms of water filtration and purification, and ensures their sustainability, through modern management regimes.

Integrated water resource management: Different users within a watershed are interdependent; therefore, integrated water resource management is essential. Upstream uses of water impact the potential of downstream users to meet their needs. Land use, agricultural patterns, and industrial development all affect water resources. A wide range of sectors, e.g., agriculture, energy, industry, fisheries, tourism, local government all must plan and coordinate strategies on the full range of developments that affect ecosystems, natural hydrology, and water consumption – with reference to expert advice and guidance of health and environment sectors.

Protecting water from contamination from household to global level: Careful disposal of waste and protection of health from contaminated water sources is a vital principle – from the personal to the international level. It includes simple hygiene tactics like good handwashing practice and safe filtration/storage of household water resources; move onto local and municipal sanitation and waste disposal systems; and also include global regimes/conventions to protect both fresh and marine water sources from transboundary waste, unsustainable resource use, and contamination. Development and implementation of water quality standards, monitoring of water quality/water-related disease indicators, are critical to protection of water sources.


More than one-third of the world's population lives within 100 kilometers of a sea shore. Coastal ecosystems include features such as wetlands, estuaries, mangroves and coral reefs – all of which provide 'services' vital to human health and well-being. Those range from the natural filtration of freshwater sources in wetlands and forests; provision of habitats for fish and other food sources to spawn and develop; provision of livelihoods and recreational sites; and provision of coastal barriers against sea level fluctuation (3). Unsustainable development of aquaculture and tourism, transport and industrial facilities, and even dams upstream, can irreversibly diminish vital coastal ecosystem services to human health. Thus, preserving the health of coastal ecosystems is vital to the health and well-being of an increasing proportion of the world's population.

  • The state of the environment; freshwater. GEO-2000: Global Environment Outlook. Nairobi, United Nations Environment Programme, 1999.
  • WHO, ed. The World Health Report 2002 : Reducing Risks, Promoting Healthy Life. Geneva, World Health Organization, 2002.
  • Marine and coastal areas - state of the environment. GEO-2000 - Global Environment Outlook. Nairobi, United Nations Environment Programme, 1999.