Water Pollution

Compiled by:
Stefanie Keller (seecon international gmbh)

Executive Summary

Water is essential for all aspects of life and the defining feature of our planet. In some regions of the world, rivers and seas have become so polluted that ecosystems and the health of plants, animals, and humans are heavily threatened. Water pollution occurs when nutrients and other materials are released, degrading the quality of the water for other users. Water pollution includes all of the waste materials that cannot be naturally broken down by water. The disposal of untreated wastewater strongly contributes to the global water pollution we are facing nowadays. Recycling domestic, agriculture and industrial wastewater together with efficient wastewater management can help reducing water pollution around the world (CORCORAN et al. 2010). Besides wastewater, there are various other factors which cause water pollution such as marine dumping and oil pollution. Only implementing adequate political, legal and economic instruments as well as global co-operation can contribute to improve global water quality.


The world is confronted with a global water quality crisis. The continuing growth of population growth and urbanisation, rapid industrialisation, and expanding and intensifying food production are all putting pressure on water resources and increasing the unregulated or illegal discharge of contaminated water within and beyond national borders (CORCORAN et al. 2010).

Water is essential for all aspects of life and the defining feature of our planet. About 97.5% of all water is found in the oceans and of the remaining freshwater only one percent is accessible for extraction and use. Functioning and healthy aquatic ecosystems provide us with a dazzling array of benefits — food, medicines, recreational amenity, shoreline protection, processing our waste, and sequestering carbon (CORCORAN et al. 2010).

unep ny water pollution

Water pollution has various causes and sources. Source: CORCORAN et al. (2010)

In some areas of the world, rivers, lakes and seas have become so polluted that ecosystems and the health of plants, animals, and humans are threatened. Pollution from agriculture, industry and domestic wastewater is making water resources, both surface water and groundwater, increasingly scarce and decreasingly poor in quality (DOPP n.y.).

In recent years, many nations have realised the problem of increasing water pollution. Some of these nations are taking steps to control or clean up the polluted waters ― yet, it remains a problem that is not tackled in many areas of the world.

Water pollution can come from several of different sources. If the pollution comes from a single source, such as an oil spill, it is called point-source pollution. If the pollution comes from many sources, it is called nonpoint-source pollution. Most types of pollution affect the immediate area surrounding the source. Sometimes the pollution may affect the environment hundreds of miles away from the source, such as nuclear waste; this is called transboundary pollution (WATER POLLUTION GUIDE 2008).

Every day, 2 million tons of sewage, industrial and agricultural waste is released into the world’s water. The United Nations estimates that the amount of wastewater produced every year is about 1,500 km3, six times more water than exists in all the rivers of the world (PACIFIC INSTITUTE 2010).

What is Water Pollution?

(Adapted from SDWF 2008)

Water pollution can be defined in several ways. Water pollution occurs when nutrients and other materials are released, degrading the quality of the water for other users. Water pollution includes all of the waste materials that cannot be naturally broken down by water. In other words, anything that is added to the water, above and beyond its capacity to break it down, is pollution. Pollution can be caused by nature itself, such as when water flows through soils with high acidity. But much more often, human actions are responsible for the pollutants that enter the water.

Wastewater’s Impact on Water Pollution

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Water pollution caused through the untreated disposal of industrial wastewater. Source: CORCORAN et al. (2010)

(Adapted from CORCORAN et al. 2010)

The way food is produced worldwide uses 70–90% of the available fresh water, returning much of this water to the system with additional nutrients and contaminants. It is a domino effect as downstream agricultural pollution is joined by human and industrial waste. This wastewater is polluting freshwater and coastal ecosystems, threatening food security, access to safe drinking and bathing water and providing a major health and environmental management challenge. Up to 90% of wastewater flows untreated into the densely populated coastal zone contributing to growing marine dead zones. A staggering 80–90% of all wastewater generated in developing countries is discharged directly into surface water bodies.

Contaminated water from inadequate wastewater management provides one the greatest health challenges restricting development and increasing poverty through costs to health care and lost labour productivity. Unregulated discharge of wastewater threats and decreases biological diversity, natural resilience and the capacity of the planet to provide fundamental ecosystem services, impacting both rural and urban populations and affecting sectors from health to industry, agriculture, fisheries and tourism. In all cases, it is the poorest that are the most severely affected.
Wastewater management — or rather the lack of it — has a direct impact on the biological diversity of aquatic ecosystems, disrupting the fundamental integrity of our life support systems, on which a wide range of sectors from urban development to food production and industry depend. It is essential that wastewater management be considered as part of integrated, ecosystem-based management that operates across sectors and borders, freshwater and marine.

Reducing Water Pollution through Wastewater Recycling

(Adapted from CORCORAN et al. 2010)

Wastewater has long been used as a resource in agriculture. The use of contaminated water in agriculture for irrigation and fertilising purposes can be managed through the implementation of various barriers which reduce the risk to both crop viability and human health. Today, an estimated 20 million hectares of land is irrigated using wastewater worldwide, particularly in arid and semiarid regions and urban areas where unpolluted water is a scarce resource. There are clear health advantages related to wastewater use in agriculture, stemming directly from the provision of food (mainly vegetables) to urban populations. It is estimated that 10% of the world’s population relies on food grown with contaminated wastewater.

Recognising wastewater as a resource has a huge positive impact on the outcome of agriculture production and reduces the water pollution by preventing the disposal of contaminated wastewater into water bodies. Reusing wastewater in agriculture can also integrate wastewater produced in industries (see also optimisation of water use in industry or in agriculture). Furthermore, the industrial sector can also reuse its own generated wastewater for various processes within its production and therefore prevent water pollution by releasing untreated wastewater into water bodies. Reusing wastewater has therefore two main advantages: it improves the living conditions of the local population through better food production and reduces the water pollution in these areas (see also recharge and reuse).

As water is extracted and used along the supply chain, both the quality and quantity of water is reduced. Source: CORCORAN et al. (2010)

Reducing Water Pollution through Efficient Wastewater Management

(Adapted from CORCORAN et al. 2010)

Under-dimensioned and aged wastewater infrastructure is already overwhelmed, and with predicted population increases and changes in the climate the situation is only going to get worse. Without better infrastructure and management, millions of people will continue to die each year and there will be further losses in biodiversity and ecosystem resilience, undermining prosperity and efforts towards a more sustainable future.

Currently, most of the wastewater infrastructure in many developing countries and fastest growing cities is either non-existent, inadequate or outdated and therefore entirely unable to keep pace with the demands of rising populations. Experience has shown that substantial investments done in the right manner can provide the required returns (see economic issues. However, finding a solution will require not only investment but also carefully integrated national to municipal water and wastewater planning that addresses the entire water chain — drinking water supply (see water sources, production and treatment of wastewater, ecosystem management, agricultural efficiency and urban planning.

Wastewater management has many associated environmental benefits, enabling ecosystems within watersheds and the productive coastal zone to thrive and deliver services on which healthy communities and economies depend. Inadequate management in turn incurs heaving costs, threatening to undermine these ecosystems. However the value of these benefits is often not calculated because they are not determined by the market, due to inadequate property rights, the presence of externalities, and the lack of adequate information. Valuation of these benefits is nevertheless necessary to justify suitable investment policies and financing mechanisms (see also policies and legal framework).

Further Causes of Global Water Pollution

(Adapted from WATER POLLUTION GUIDE 2008)

Besides the global water pollution caused by inadequate wastewater management, there are other factors which contribute to the global water pollution:

  • Eutrophication: Eutrophication is when the environment becomes enriched with nutrients through wastewater or fertilisers which are released to water bodies. This can be a problem in marine habitats such as lakes as it can cause algal blooms. Fertilisers are often used in farming, sometimes these fertilisers run-off into nearby water causing an increase in nutrient levels. This causes phytoplankton to grow and reproduce more rapidly, resulting in algal blooms. This bloom of algae disrupts normal ecosystem functioning and causes many problems.
  • Industrial Waste: Industry is a huge source of water pollution, it produces pollutants that are extremely harmful to people and the environment. Many industrial facilities use freshwater to carry away waste from the plant and into rivers, lakes and oceans.
  • Marine Dumping: Dumping of litter in the sea can cause huge problems to the environment and human beings. A good example is the “Great Pacific Garbage Patch”, also described as the Pacific Trash Vortex. This is a gyre of marine litter in the central North Pacific Ocean. The patch extends over a very wide area, with estimates ranging from an area the size of the state of Texas to one larger than the continental United States. The patch is characterised by exceptionally high concentrations of pelagic plastics, chemical sludge, and other debris that have been trapped by the currents of the North Pacific Gyre. Some of these long-lasting plastics end up in the stomachs of marine birds and animals. These toxin-containing plastic pieces are also eaten by jellyfish, which are then eaten by larger fish. Many of these fish are then consumed by humans, resulting in their ingestion of toxic chemicals (WIKIPEDIA 2010).
  • Oil Pollution: Oceans are polluted by oil on a daily basis from oil spills, routine shipping, run-offs and dumping. Oil spills make up about 12% of the oil that enters the ocean. The rest come from shipping travel, drains and dumping. An oil spill from a tanker is a severe problem because there is such a huge quantity of oil being split into one place.
  • Radioactive Waste: Nuclear waste is produced from industrial, medical and scientific processes that use radioactive material. Nuclear waste can have detrimental effects on marine habitats.
  • Underground Storage Leakages: A tank or piping network that has at least 10 percent of its volume underground is known as an underground storage tank (UST). They often store substances such as petroleum, that are harmful to the surrounding environment should it become contaminated. Many UST’s constructed before 1980 are made from steel pipes that are directly exposed to the environment. Over time the steel corrodes and causes leakages, affecting surrounding soil and groundwater.
  • Global Warming: An increase in water temperature can result in the death of many aquatic organisms and disrupt many marine habitats. For example, a rise in water temperatures causes coral bleaching of reefs around the world. This is when the coral expels the microorganisms of which it is dependent on. This can result in great damage to coral reefs and subsequently, all the marine life that depends on it.
  • Atmospheric Deposition: Atmospheric deposition is the pollution of water caused by air pollution. In the atmosphere, water particles mix with carbon dioxide sulphur dioxide and nitrogen oxides, this forms a weak acid. Air pollution means that water vapour absorbs more of these gases and becomes even more acidic. When it rains the water is polluted with these gases, this is called acid rain. When acid rain pollutes marine habitats such as rivers and lakes, aquatic life is harmed.
  • Noise Pollution: Over the past decades, an increase in water traffic, oil extraction, sonar system etc. have lead an increasing noise pollution of the oceans. Sound travels much faster under water than on air, and thus also much farther. This increasing noise has adverse impacts on aquatic live that are not yet entirely clear but are significant.

Responses to Water Pollution

(Adapted from KRAEMER et al. 2001)

Political approaches: Ineffective regulatory oversight, institutional failures and lack of political commitment are often mentioned as some of the most significant causes of water pollution problems. Therefore, a critical step towards the protection of water resources is the creation of will and commitment among political parties at all levels, to seriously invest human and financial capital in the protection of freshwater and related ecosystems and to consider the polluter pays principle in all relevant water policy formulation.

Legal Instruments: Legal instruments, so-called command and control strategies have been used widely over the past 20 years and still remain important in several high-income as well as developing countries. The approach of command and control, however, is yielding fewer benefits per unit of expenditure in some industrialised countries, while developing countries often lack the necessary preconditions for implementing pollution control measures (see also enforcement). Even where court orders have sentenced closure of polluting industries, these often have silently reopened for economic and employment reasons. In some cases, the effectiveness of traditional enforcement measures such as inspections and penalties has been successfully strengthened through combination with other instruments such as public disclosure programmes and economic instruments.

Economic Instruments: A shift to economic market based instruments to combat water pollution is being experienced. Water charges are one of the most frequently used economic instruments and should be high enough to effectively induce changes in behaviour and foster preventive measures. It is recommended that such measures should be phased in gradually to take due account of the social and economic implications. An immediate response to high charges is not as easy to achieve in lower income countries as in industrialised ones. On the other hand, the effect of charges set at a fairly low level, as in some European countries in transition, is questionable. In this case, charges are low due to the present low economic status and the state of industry. Water pollution cannot be addressed by price and market-based schemes alone. Experience points to the combination of planning, regulation (e.g. monitoring) and economic instruments (e.g. charges, tradable permits). The existence of direct regulations appears to be a necessary pre-condition for the successful implementation of economic instruments (see also policies and legal framework).

Co-operation: Several examples of co-operation among stakeholders such as bilateral agreements, river commissions, water pollution control through public information and participation and co-operation between private companies and local stakeholders. The involvement of user and community-based organisations, which are expressions of civil society, is also increasingly recognised as a central principle in the protection of water resources. In this context, water user associations and farmer groups need to be properly trained and included in the debate.

Paradigm Shift: Single sector approaches such as wastewater treatment or river basin management are limited in their actions. To save and recycle water, regain resources and to protect aquatic ecosystems, the whole water cycle needs to be taken into account in an integrated, holistic way – linking up reuse-oriented sanitation approaches with IWRM. See SSWM concept.


CORCORAN, E. (Editor); NELLEMANN, C. (Editor); BAKER, E. (Editor); BOS, R. (Editor); OSBORN, D. (Editor); SAVELLI, H. (Editor) (2010): Sick Water? The central role of wastewater management in sustainable development. A Rapid Response Assessment. United Nations Environment Programme (UNEP), UN-HABITAT, GRID-Arendal. URL [Accessed: 05.05.2010].

DOPP (Editor) (n.y.): TED Analysis Cases. Sea Water Pollution - Cases Analysis. Washington: American University. URL [Accessed: 28.09.2010].

KRAEMER, A.; CHOUDHURY, K.; KAMPA, E. (2001): Protecting Water Resources: Pollution Prevention. (= Thematic Background Paper). International Conference on Freshwater in Bonn. URL [Accessed: 21.04.2012].

PACIFIC INSTITUTE (Editor) (2010): World Water Quality Facts And Statistics. Oakland: Pacific Institute. URL [Accessed: 28.09.2010].

SDWF (Editor) (2008): Water Pollution. Saskatoon: Safe Drinking Water Foundation. URL [Accessed: 28.09.2010].

WATER POLLUTION GUIDE (Editor) (2008): Types of Water Pollution. URL [Accessed: 28.09.2010].

WIKIPEDIA (Editor) (2010): The Great Pacific Garbage Patch. URL [Accessed: 28.10.2010].

Further Readings

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CORCORAN, E. (Editor); NELLEMANN, C. (Editor); BAKER, E. (Editor); BOS, R. (Editor); OSBORN, D. (Editor); SAVELLI, H. (Editor) (2010): Sick Water? The central role of wastewater management in sustainable development. A Rapid Response Assessment. United Nations Environment Programme (UNEP), UN-HABITAT, GRID-Arendal. URL [Accessed: 05.05.2010].

This book not only identifies the threats to human and ecological health that water pollution has and highlights the consequences of inaction, but also presents opportunities, where appropriate policy and management responses over the short and longer term can trigger employment, support livelihoods, boost public and ecosystem health and contribute to more intelligent water management.

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PACIFIC INSTITUTE (Editor) (2010): World Water Quality Facts And Statistics. Oakland: Pacific Institute. URL [Accessed: 28.09.2010].

This factsheet contains important facts regarding global water quality and its causes and effects.

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SDWF (Editor) (2008): Water Pollution. Saskatoon: Safe Drinking Water Foundation. URL [Accessed: 28.09.2010].

This paper gives a good introduction to the water pollution with its impacts and how to improve the situation of household level.

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NATURE (Editor); NARAIN, S. (2012): Sanitation for All. In: Nature: International Weekly Journal of Science 486, 185. URL [Accessed: 19.06.2012].

Water pollution from sewage is causing great damage to India. The nation needs to complete its waste systems and reinvent toilet technologies.

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Rosemarin, A. (2010): Peak Phosphorus and the Eutrophication of Surface Waters: A Symptom of Disconnected Agricultural and Sanitation Policies . In: On the Water Fron 2. URL [Accessed: 18.03.2013].

This paper is discussing the limited mineral sources of phosphorus, their management in human systems, the respective flows and net losses and the need for increased efficiency and recycling. The paper explores the policy and technology disconnections between the practices in using phos¬phorus fertiliser in agriculture, the control of phosphorus in effluents, the management of the mineral reserves and products therein and the need for environment-friendly recycling systems.

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Graham, J.; Polizotto, M.L. (2013): Pit Latrines and Their Impacts on Groundwater Quality: a systematic Review. Advance Publication. In: Environmental Health Perspectives. URL [Accessed: 09.04.2013].

This study reviews empirical studies on the impact of pit latrines on groundwater quality and identifies knowledge gaps regarding the potential and consequences of groundwater contamination by latrines.

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SPERLING, M. von (2007): Wastewater Characteristics, Treatment and Disposal. (= Biological Wastewater Treatment Series, 1). London: International Water Association (IWA) Publishing. URL [Accessed: 01.11.2013].

Wastewater Characteristics, Treatment and Disposal is the first volume in the series Biological Wastewater Treatment, presenting an integrated view of water quality and wastewater treatment. This book covers the following topics: wastewater characteristics (flow and major constituents), impact of wastewater discharges to rivers and lakes, overview of wastewater treatment systems, complementary items in planning studies.

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SPERLING, M. von (2007): Basic Principles of Wastewater Treatment. (= Biological Wastewater Treatment Series, 2). London: International Water Association (IWA) Publishing. URL [Accessed: 01.11.2013].

Basic Principles of Wastewater Treatment is the second volume in the series Biological Wastewater Treatment, and focusses on the unit operations and processes associated with biological wastewater treatment. The major topics covered are: microbiology and ecology of wastewater treatment, reaction kinetics and reactor hydraulics, conversion of organic and inorganic matter, sedimentation, aeration.

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ANDREOLI, C.V. (Editor); SPERLING, M. von (Editor); FERNANDES, F. (Editor) (2007): Sludge Treatment and Disposal. (= Biological Wastewater Treatment Series, 6). London: International Water Association (IWA) Publishing. URL [Accessed: 01.11.2013].

Sludge Treatment and Disposal is the sixth volume in the series Biological Wastewater Treatment. The book covers in a clear and informative way the sludge characteristics, production, treatment (thickening, dewatering, stabilisation, pathogens removal) and disposal (land application for agricultural purposes, sanitary landfills, landfarming and other methods). Environmental and public health issues are also fully described.

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SPERLING, M. von; LEMOS CHERNICHARO, C.A. de (2005): Biological Wastewater Treatment in Warm Climate Regions Volume 2. London: International Water Association (IWA) Publishing. URL [Accessed: 01.11.2013].

Biological Wastewater Treatment in Warm Climate Regions gives a state-of-the-art presentation of the science and technology of biological wastewater treatment, particularly domestic sewage. The book covers the main treatment processes used worldwide with wastewater treatment in warm climate regions given a particular emphasis where simple, affordable and sustainable solutions are required. The 55 chapters are divided into 7 parts over two volumes: Volume One (also available in the SSWM library): Introduction to wastewater characteristics, treatment and disposal; Basic principles of wastewater treatment; Stabilisation ponds; Anaerobic reactors; Volume Two: Activated sludge; Aerobic biofilm reactors; Sludge treatment and disposal.

Case Studies

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KRAEMER, A.; CHOUDHURY, K.; KAMPA, E. (2001): Protecting Water Resources: Pollution Prevention. (= Thematic Background Paper). International Conference on Freshwater in Bonn. URL [Accessed: 21.04.2012].

This thematic background paper for the International Conference on Freshwater in Bonn in December 2001 is a collection and analysis of relevant information on pressures, state and responses of both groundwater and surface water pollution with special emphasis given to regional conditions, frames and problems. To point out success stories and lessons learnt, case studies have been selected.

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IWMI (Editor) (2012): Changing to Biofuel Crops Makes Productive Use of Contaminated Water. Sri Lanka: International Water Management Institute (IWMI). URL [Accessed: 26.03.2012].

Ten years ago, Thai epidemiologists noticed unusual clusters of kidney disease among elderly people around the town of Mae Sot. Heavy metal poisoning was suspected. A research team, including scientists from the International Water Management Institute (IWMI), demonstrated that an irrigation system dissecting an area rich in minerals was contaminating local rice. Thanks to their efforts, farmers received compensation and training so that they could switch to growing inedible crops valuable for biofuels.

Awareness Raising Material

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GEORGE, R. (2012): Dirty Little Secret: The Loo that Saves Lives in Liberia. London: The Guardian. URL [Accessed: 13.02.2012].

Diarrhoea kills more children than HIV/Aids, tuberculosis and malaria combined – and its main cause is food and water contaminated with human waste. Liberia's president is trying to change all that.

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UN Water; UN Water (Editor) (2013): Water Quality Factsheet. UN Water. URL [Accessed: 09.04.2013].

Thematic factsheet. Every day, 2 million tons of human wastes are disposed of in watercourses, and in developing countries 70 % of industrial wastes are dumped untreated into waters where they pollute the usable water supply. But not only industry contaminates our water resources, so do also agriculture. The contribution of the food sector to the production of organic water pollutants, are in high-income countries 40 % and in low-income countries 54 %.

Important Weblinks

http://www.water-pollution.org.uk/ [Accessed: 28.09.2010]

This guide gives a good overview of the different types of water pollution.

http://maps.grida.no/theme/freshwater [Accessed: 21.04.2010]

This website contains a number of high-quality maps on different subjects, amongst them also on freshwater availability, water scarcity etc.