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Safe drinking water and sanitation and human health

Goal 4: Reduce child mortality
Goal 5: Improve maternal health
Goal 6: Combat HIV/AIDS, malaria and other diseases
Goal 7: Target 10/WSSD Plan of Implementation: Reduce by half, by 2015, the proportion of people without sustainable access to safe drinking water and basic sanitation

Freshwater and human health are intimately linked. Contaminated drinking water is one of the major causes of sickness and death. The vast majority of water-related deaths occur in developing countries and many are caused by relatively easily-treated and preventable diarrhoeal diseases. Nine out of 10 of the people affected are children under five (Prüss and others 2002).

Although direct human consumption and sanitation are among the smallest uses of freshwater on an absolute scale, providing freshwater of the quantity and quality required is one of humanity’s greatest continuing challenges. The global population is now more than 6.3 billion people, and the number is growing by about 77 million people every year (UNPD 2003). The availability of safe drinking water is critical to meeting the goals for enhancing human well-being and security.
The proportion of people served with some form of improved water supply rose from 78 per cent in 1990 to 82 per cent in 2000. Over the same period the world’s population with access to improved sanitation increased from 51 per cent to 61 per cent (WHO and UNICEF 2003). Despite these gains, about 1.1 billion people in the world lacked access to safe drinking water in 2000, while another 2.4 billion lacked access to improved sanitation (see the GEO Indicators section). As expressed by the UN Secretary-General Kofi Annan in 2000: “No single measure would do more to reduce disease and save lives in the developing world than bringing safe water and adequate sanitation to all” (UN 2000b).

Freshwater distributes pollutants, and many disease-causing micro-organisms (pathogens) and their vectors live in it. Infants and children are especially susceptible to sickness associated with contaminated drinking water and inadequate sanitation, particularly to diarrhoeal diseases. Lack of safe drinking water and sanitation also has obvious implications for maternal health and can exacerbate illnesses which affect the immune system, such as HIV/AIDS. Improved sanitation alone could reduce related deaths by up to 60 per cent, episodes of diarrhoea by up to 40 per cent, and stunting of child growth by up to 50 per cent (WEHAB Working Group 2002).
Illness and disability caused by water-related diseases contribute to a huge loss in human economic productivity. The Disability-Adjusted Life Year (DALY) is a unit of measurement reflecting lost years of healthy life; the WHO has used it as a measure to report on the impact of some water-associated diseases on health (WHO and UNICEF 2000). By far the largest impact is caused by malaria (42.3 million DALYs), followed by lymphatic filariasis (5.64 million DALYs), water-borne diseases such as schistosomiasis (1.76 million DALYs), and related infections (1.42 million DALYs). Various technologies, however, including membrane technologies (Box 6), offer solutions and can significantly improve drinking water quality.

Box 6: Technology at work – membrane technology

Expanding industrialization over the last two centuries has Mimicking nature (membranes in seagull beaks,plant roots and kidneys), artificial membranes can be used to purify water. Whereas natural permeation through a membrane will take place from low to high salt concentration,reverse osmosis is the application of pressure to force water to move from high to low salt concentration. This technology can be used for desalinating water. With the wide range of membranes now available most contaminants of concern can be separated from raw water sources. Membranes come in a range of pore sizes and permeability from micro-filtration, ultra-filtration, nanofiltration to hyper-filtration (reverse osmosis) and can filter out corresponding particle sizes (see diagram below). Membranes are also available in various materials – polymers, organo-mineral, ceramic or metallic – to cope with differing conditions. They are used to produce safe drinking water from brackish water, remove turbidity, algae, pathogens, viruses, and metal contaminants, clean industrial effluent, concentrate, purify or fractionate temperature sensitive solutions in the food, drug and biotechnology industries, and are used in artificial kidneys. Fouling impedes performance, but several cleaning mechanisms are available such as back flushing, air bubbles and chemicals. The costs of large-scale application of membrane technology for the desalinization of saline water to produce drinking water are double those of conventional treatment costs. However, the potential for lower cost applications in the removal of bacterial and parasitic pathogens from surface water using micro-filtration are very promising. For example, off-cuts from hollow-fibre membrane micro-filters are now being developed for use in developing countries for water purification at household and community level.

Pressure-driven membrane types with associated pore sizes (indicated by box outline) and the type of
contaminant that they can remove.

Source: ETC 2003

 

Existing water and sanitation systems are inadequate for 30–60 per cent of the urban population, mainly in developing countries. The situation is most severe for the estimated 924 million people living in urban slums (UN-Habitat 2003a). There is a link between the urban population who do not have access to clean water through reliable piped water service, and poverty, partly due to the fact that low-income groups often have to buy their water from vendors at greatly inflated prices. People on a low income end up paying two to 50 times more for a litre of water than higher income groups, who are connected to often heavily subsidized water infrastructure (UN-Habitat 2003b). In some cities this difference is even higher (UNEP in press) (Figure 5). This further reduces the limited financial resources of poor people and their coping capacity. It is not surprising that many turn to water supplies that may not be clean, such as a local river, to meet their daily needs.

Privatization of water supply and sanitation is often seen as a way to improve services and lighten the burden on scarce public finances (UN-Habitat 2003b). Although the aim is to provide water and sanitation services more efficiently through market mechanisms, several high profile privatization initiatives in developing countries have actually resulted in price increases that made the cost of access to safe water and sanitation prohibitive for the poor (UN-Habitat 2003b). The more vulnerable members of society, particularly poor women, are the worst affected by such changes to water and sanitation pricing, and the stresses that they cause to people’s livelihoods (Grossman and others 2003).

Figure 5: The price urban residents pay for water in selected regions and the factor difference in price for rich and poor living in the same city for selected cities

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