Contaminated Surface Water

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Description

Every human needs about 20 liters of freshwater a day for basic survival (drinking and cooking) and an additional 50 to 150 liters for basic household use.1 With growing populations and an overall increase in living standards, not only is the overall demand for freshwater pushing limits (one third of world now lives in areas of “water stress”2) but increasing pollution from urban, industrial and agricultural sources is making available resources either unusable or – if there is no alternative – dangerous to health. Almost 5 million deaths in the developing world annually are due to water related diseases, much of this being preventable with adequate supplies of safe water.3

Context

Rural communities around the world traditionally take their water supply from rivers or from shallow dug wells. Growing concentrations of people combined with the increasing industrialization of land use have resulted in many major rivers becoming highly polluted. Sometimes the pollution levels even cause the rivers to become biologically dead and poisonous to drink. In areas where surface water is not readily available, groundwater is the primary water source and serves an estimated 20% of the global population who live in arid and semi-arid regions.4 Underground aquifers are slower to show problems but now are increasingly affected by contamination that is extremely difficult to undo.

Treatment of contaminated drinking water is possible at an urban or a community scale, but it requires financial and human resources not often available. Even when provided, the quality after treatment is often still uncertain and remaining subtle pollutants in trace quantities can still pose health risks (such as the infamous “gender benders” which are believed to upset human hormone balance). The efforts to reduce or prevent pollution of critical waters are numerous, but the scale of the challenges is enormous. River basins containing tens of millions of residents are almost unmanageable, given the weak capability and tools that are normally available and the low priority that is usually given to reducing pollution. This attitude is changing as the human and economic costs are recognized, but the timescale for major improvements is probably decades, at least in the larger systems.

Exposure Pathways

Key pollutants in the water systems are typically pathogens arising from human waste (bacteria and viruses), heavy metals and organic chemicals from industrial waste. Ingestion of pathogens through drinking contaminated water or with food prepared using contaminated water is the most common pathway. Eating fish from contaminated waters can be risky, since they can absorb and concentrate both pathogens and toxics such as heavy metals and persistent organics. In addition, human health may be affected by crops that take up pollutants from contaminated water used for irrigation or from land flooded by polluted rivers.

Health Effects

Pathogens can cause a variety of gastro-intestinal diseases, which can be fatal to babies and to other vulnerable populations. WHO data shows water pollution is one of the greatest causes of mortality that can be linked to environmental factors. Boiling water can destroy most pathogens, however this requires fuel, a commodity often in short supply in poor households. (Some of these diseases may be related to poor hygiene rather than direct ingestion of contaminated water but this in turn is often a result of the lack of adequate amounts of clean water.)

Toxic contaminants in fish or other foods are less likely to cause acute poisoning but can have serious long-term effects, depending on the pollutants and the doses. Understandably, fishing communities along rivers are particularly at risk since they have a steady diet of the local fish over many years.

Some site that have been noted as examples of the problem

Water quality problems are affecting virtually all of the developing world’s major rivers. Northern India suffers immense flooding in its river systems but in the dry season, pollution problems dominate, especially in the upper reaches, including around New Delhi. In China, industrialization has created serious problems in rivers such as the Huai, where large sections of the river are acknowledged to be in the lowest possible water quality classification. Similar problems exist in many other urbanized waterways.

Even where the main stem of a river remains acceptable, serious problems are often seen in the smaller branches – usually local streams which have become urban drains (and dumps or “rubbish tips”). Unfortunately, these urban drains are also the main source of water for drinking and daily use for poor communities along their banks. This problem will only worsen as competition for limited or degraded resources intensifies. Over the next few decades, up to two-thirds of the world’s population will be affected by water scarcity.5

What is Being Done

India has a Ganga Action Plan, launched in the 1980’s to reduce the pollution of the river Ganges, but measurable progress has been slow, despite the expenditure of hundreds of millions of rupees. In China, investment of billions of dollars over twenty years (along with closure or relocation of many industries) has produced a significant improvement in the Huangpu River in the centre of Shanghai, but increasing upstream loads from urbanization and industry are causing measurable deterioration even in the mighty Yangtze. These programs reflect the decades of effort and investment that are needed. The experience of the west on rivers such as the Rhine and the Thames has demonstrated that rehabilitation is eventually possible.

Better off communities can afford water treatment systems and wealthier people can take avoidance measures such as tankered or bottled water from safe sources, but the poor have limited options and need to look towards provisions of public water supplies. Unfortunately, many developing nations face their own public water challenges. Where the problem is localized or can be linked clearly to a few specific sources or pollutants, smaller scale interventions can be effective, in terms both of achieving some improvement to water quality and also of starting a longer-term process. However, large amounts of time and resources are typically needed.

Footnotes

1 Gleick, Peter H. “Basic Water Requirements for Human Activities: Meeting Basic Needs.” Pacific Institute for Studies in Development, Environment, and Security. International Water Resources Association. Water International, 21 (1996) 83-92.
2 Kirby, Alex. “Water scarity: A looming crisis?” BBC. October 19, 2004. Available at http://news.bbc.co.uk/2/hi/science/nature/3747724.stm
3 Pruss-Ustun, Annette; Bos, Robert; Gore, Fiona; Bartram, Jamie. “Safer Water, Better Health: Costs, benefits and sustainability of interventions to protect and promote health.” World Health
Organization. 2008.
4 “Vital Water Graphics: Problems related to freshwater resources.” United Nations Environment Programme. 2002. Available at http://www.unep.org/dewa/assessments/ecosystems/water/vitalwater/20.htm
5 Rijsberman, Frank R. “Water scarcity: Fact or fiction?” Agricultural Water Management. 80.1-3, (2006) 5-22.

Additional Photos

 

Chromium polluted surface water. India. Photo by Blacksmith Institute.

 

 

 

Polluted surface water. Dar es Saalam, Tanzania. Photo by Blacksmith Insitute.

 

My Source: http://www.worstpolluted.org/projects_reports/display/57

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