Water Pollution IAS Target

Water Pollution

29 Jul 2020

Category : Environmental Issue

Topic: Water Pollution

Water pollution is caused by the presence of toxic chemicals in groundwater and biological agents that exceed what is naturally found in the water and may pose a threat to human health or the environment. Besides, water pollution may consist of chemicals present into the water bodies as a result of various human activities. Any amount of those chemicals pollutes the water, regardless of the harm they may pose to the environment and human health.
Water pollution is the contamination of water bodies, generally as a result of human activities. Water bodies include such as oceans, lakes, aquifers and groundwater. Water pollution results when contaminants come into the contact of natural environment. For example, generating inadequately treated wastewater into natural water bodies may lead to degradation of aquatic ecosystems. In turn, this can affect the health of the people who are living downstream. They may use the same polluted river water for various regular activities like drinking, bathing and irrigation. Water pollution is the leading worldwide which may leads to death and disease, e.g. due to water-borne diseases.

Sources of Water Pollution

Sources of water pollution such as :-

  • Point Sources
    Point sources have one identifiable cause of the pollution, like a wastewater treatment plant or stream and a storm drain.
  • Non-point Sources
    Non-point sources are more diffuse, for example agricultural runoff. Pollution is the result of the cumulative effect over time. All plants and organisms living in or being exposed to polluted water bodies can be affected. The effects can damage the species and affect the natural biological communities they are part of it.

Water Pollution is divided into-

Surface Water Pollution Surface water pollution is considered the tangible form of pollution and it can be seen floating on waters in lakes, streams, and oceans. Trash from human consumption, for example plastic, water bottles and other waste products, is the most evident on water surfaces. Such kind of pollution comes from oil spills and gasoline waste, which not only float on the surface, but also affect the water and its inhabitants. Water contaminants from fracking such as a toxic chemicals, methane, benzene, and radiation.
Groundwater Pollution This type of pollution is becoming more and more relevant because it impact the aquifers below the soil and the drinking water. Groundwater pollution generally occurs due to highly toxic chemicals and pesticides from farming that leak through the ground to infect the wells and aquifers below the surface.
Microbial Pollution Microbiological pollution is the natural form of water pollution happens due to microorganisms in uncured water. These microorganisms are not harmful, but some bacteria, viruses, and protozoa may prone to serious diseases like cholera and typhoid. This is a significant problem for those who have no clean drinking water and facilities to disinfect the water.
Oxygen Depletion Pollution Microorganisms that bloom in water feed on biodegradable substances. When there is a flow of biodegradable material from such things as waste or erosion from farming, the numbers of these microorganisms enhance and use the obtainable oxygen. When these oxygen levels are depleted, anaerobic microorganisms thrive and harmless aerobic microorganisms die. Mostly these types of organisms generate hazardous chemicals like sulfide and ammonia.
Nutrient Pollution Nutrients are generally found in wastewater as well as fertilizers. These may cause excess vegetation in the water like algae and weeds, using up the oxygen in the water and hurting the surrounding marine life and other organisms in the water.
Suspended Matter Pollution This type of pollution happens when pollutants enter the water and don't blend in with the water molecules. These suspended particles form fine silt on the waterbed, harming the marine life by taking away the nutrients and disturbing their habitat.
Chemical Pollution Because of nature of industry these days and the mass production in industrial farms and plants, we have lots of chemical run-off that flows into the nearby rivers and water sources. Metals and solvents flow out of factories and enter the water, polluting the water and harming the wildlife. Pesticides from farms are like poison to the wildlife in the water and kill the aquatic life.
Suppose, birds or humans eat these infected fish, the toxins are transferred to us and we swallow these dangerous pesticides and toxins, affecting our health. Petroleum is a different kind of chemical pollutant that dramatically affects the aquatic life. This oil leads to death of the fish and marine life and sticks to the feathers of birds, causing them to lose their ability to fly.

Reasons of Water Pollution

Industrial and manufacturing activities Industries generate a big amount of waste which contains toxic chemicals and pollutants which can cause air, water and land pollution and damage our environment. They contain pollutants lke lead, mercury, sulfur, asbestos, nitrates, and many other harmful chemicals.
Many industries do not have a proper waste management system and discharge the waste in the water bodies. The toxic chemicals can easily change the color of water, enchance the number of minerals, also known as eutrophication. It also change the temperature of water and pose a serious hazard to water organisms.
Sewage and wastewater The sewage and wastewater that is produced by each household is chemically treated and discharge into the sea with fresh water. The sewage water carries harmful bacteria and chemicals that affect the human health. The sewers of cities house several pathogens and thereby diseases.
Microorganisms in water are known to be causes of some very deadly diseases and become the breeding grounds for other creatures that act as carriers. A very common example of this process would be Malaria.
Mining activities Mining is the process of crushing the rock and extracting coal and other minerals from underground. These elements when extracted in the raw form contains harmful chemicals and can increase the number of toxic elements which merged with water which may result in serious health problems.
Marine dumping The garbage produced by each household in the form of paper, aluminum, rubber, glass, plastic, food, solid waste, e-waste, etc., is gathered and discharged into the sea in some countries. These items take around 2 weeks to 200 years to decompose. When such items enter the sea, they not only cause water pollution but also harm animals in the sea.
Accidental oil leakage Oil spill poses a huge concern as a large amount of oil enters the sea and does not dissolve with water; thereby creates problem for local marine wildlife such as fish, birds and other organism.
Consumption of fossil fuels Fossil fuels like coal and oil when burnt produce a substantial amount of ash in the atmosphere. The particles which contain toxic chemicals when mixed with water vapor result in acid rain. Also, carbon dioxide is released from the burning of fossil fuels which result in global warming.
Agricultural activities Chemical fertilizers and pesticides are used by farmers to protect crops from insects and bacteria. They are useful for the plant’s growth. Though, when these chemicals are mixed up with water produce chemicals which affect the plants and animals .Also, when it rains, the chemicals merge with rainwater and flow down into canals and rivers which pose serious damages for water bodies.
Pollution Acid rain, climate change and global warming also makes the water harmful to the environment. Due to air pollution acid rain occurs which is toxic in nature.
Anthropogenic waste The River sustains the human population in a region where it flows and these people have shat into the river for years and years. The sewage from the houses of all these people ends up in the Rivers. Along with the human faeces, we have chemicals too such as the detergents and soaps we use regularly. This sewage has a higher organic load and therefore at least to some extent, the river can easily tackle the water pollution, but when merged with other pollutants, our River does not stand a chance.
Religious and cultural values Taking a dip in the sacred water of Ganga is considered to wash out all your sins and to this end, many number of people gather along its banks during festivities to ensure their righteousness. In addition to this, since time immemorial, people have supposed dying by the Ganga River as a sure shot way to reach paradise. Therefore the sights of dead bodies floating by on the river are a common sight. People dive in rivers in the hope of paradise, but decaying corpses are host to many dangerous bacteria and viruses.
Storing water by constructing Dams and Pumping Station: The human population has been growing since the advent of technology and the growth does not look like it’s going to stop anytime soon. To feed this ever-increasing population, along the river Ganga many dams and irrigation pumping stations have been constructed. Such dams decrease the downstream flow severely affecting life downstream and upstream too. The negative effects of dams can be seen by analysing the decline of Gangetic Dolphin’s population
Urbanization and migration As the population has grown, so has the need for housing, food, and cloth. As more cities and towns are developed, they have resulted in increasing use of fertilizers to produce more food, soil erosion due to deforestation, increase in construction activities, insufficient sewer collection, and treatment, landfills as more garbage is generated, increase in chemicals from industries to produce more materials.
Leakage from the landfills Landfills are nothing but a massive heap of garbage that produces the bad smell and can be seen across the city. When it rains, the landfills may leak and the leaking landfills can infect the underground water with a large variety of contaminants.
Faunal waste The waste produced by animals is washed away into the rivers when it rains. It gets mixed up with other harmful chemicals and causes various water-borne diseases like cholera, diarrhea, jaundice, dysentery and typhoid.
Thermal and Radiation Pollution Power plants – thermal and nuclear, chemical and other industries use much water for cooling purposes, and the used hot water is drained into rivers, streams or oceans. Discharge of hot water may increase the temperature of the receiving water by 10 to 15 °C above the ambient water temperature. This is thermal pollution. Increase in water temperature decreases dissolved oxygen in the water. Unlike terrestrial organisms, aquatic organisms are adapted to a uniform steady temperature of the environment. A sudden rise in temperature kills fishes and other aquatic animals.

One of the best ways to reduce thermal pollution is to fill the hot water in cooling ponds, permit the water to cool before generating into any receiving water body
Nuclear accidents near water bodies or during natural calamities like tsunami and earthquakes pose the risk of radiation leakage (radiation exposure) into water bodies. E.g. Fukushima Daiichi nuclear disaster. Radiation exposure causes mutations in the DNA of marine organisms. If those mutations are not repaired, the cell may turn cancerous. Radioactive iodine tends to be absorbed by the thyroid gland and can cause thyroid cancer.

Influence of Water Pollution on Flora and Fauna

  • Increase in Chemically-toxic elements
    Due to water pollution, the river Ganga and others rivers which is supposed by Indians as a holy river in which they take a holy dip to purify themselves has also become highly polluted. If today, the river Hooghly is considered among the most polluted rivers in the world, it is only due to water pollution. Some time ago, the water in the Gomati River in Lucknow had become toxic and polluted at a time that dead fish floating all through it had become a common scenario.
  • Decreasing growth of Aquatic Flora
    Aquatic plants get affected due to water pollution. Due to plethora of moss in the polluted water of the rivers, the sun light fails to reach to the depths of the river which affects the growth of aquatic plants in the lack of photosynthesis. In the polluted water of the rivers, some aquatic weed as aquatic ferns and water hyacinth begins increasing. Similarly, the sewage water getting mixed into the water of the rivers, helps in the increase of fungus, algae, bacteria, etc which begins to erupt faster.
  • Reducing life supporting gases like oxygen, co2 etc
    Increasing pollution in the sea and oceanic areas has become a threat today. Polluted water made the life of aquatic animals miserable. Water pollution reduces the level of oxygen in it. Different varieties of fish are the most affected creatures due to water pollution. Fish and other aquatic organisms start dying due to lack of oxygen in the polluted water. Hydrocarbons in the oil disperse on the surface of the oceans due to which marine and aquatic organisms do not get the oxygen and they die eventually. Things have become so alarming that many aquatic species are at the point of extinction. Polluted water also negatively impacts the breeding power of aquatic life. It makes fish and plants deficient in their ability to regenerate and reproduce. Further, animals fall prey to a variety of diseases due to drinking polluted water.
  • Spoiling Natural beauty
    Contaminated water is not only unsuitable for drinking but also for agriculture purposes. It is also responsible for destroying the beauty of the lakes and rivers.

Effects of Water Pollution on Public Health

  • Spreading various life-threatening diseases
    Microbes, toxins and water containing unnecessary amounts of salts give rise to many diseases. Around the globe more than 80 per cent of diseases are due directly or indirectly to polluted water. As per an estimate, almost 2.5 million people in over 34000 villages of India are suffering from cholera. Contaminated water contains a variety of disease-causing bacteria that results in several types of ailment.
    A large number of diseases in India can be attributed to drinking of sewage mixed water. Various diseases such as polio, cholera, patches, jaundice, fever, viral fever etc are spread through polluted water. Polluted water contains lead which when consumed by the humans while drinking water leads to producing various ailments such as joint pain, kidney disease and heart disease in them. The waterborne diseases are infectious which spread primarily from polluted water. Hepatitis, cholera, dysentery and typhoid are the common waterborne diseases, which affect the majority of tropical area. Apart from diarrhoea, and breathing problems, drinking polluted water causes skin diseases. If the polluted water gets stagnated, it becomes a breeding ground for mosquito and many other parasites which are very common in tropical areas.
    Children often get sick if they drink infected water and sometimes they even die due to intensity of the diseases. Polluted water is like poison for human beings. Large amounts of chloride in drinking water deform the spine which becomes snaky and their teeth go yellow, start falling and moreover their hands and feet lose flexibility of the bones and their body deforms. Water pollution leads to kidney diseases too. A large amount of sulphide in polluted water is the cause of various respiratory diseases and drinking water contaminated with urea increases intestinal disorder. Thus continuous intake of polluted drinking water is the reasons behind various stomach related disorders and other diseases like lumps in throat, tooth decay, etc.
    Composition of nitrate resulting from fertilizer and chemicals used in pit latrines, agricultural lands and waste dumps causes contamination of the groundwater. Such contaminated drinking water becomes the reason of blue baby disease in kids which changes their skin colour. In this disease, nitrate present in groundwater decrease the oxygen carrying capacity of haemoglobin in babies, leading to their death. Radioactive substances released from nuclear explosions enter the water bodies and makes drinking water severely contaminated. If any person uses this water can become a victim of dreadful diseases like cancer. Continuous utilization of this water can make the children disable.
  • Rendering drinking water unsafe
    It is due to water pollution, the drinking water becomes smells bad. Micro-organisms present in the water gives the water unpalatable taste. When organic substances in the polluted water start decaying, it releases harmful gases which give the water very bad smell.
  • Affecting Industrial units
    Due to water pollution, the ability of industries reduce because it affects the performance of industrial units. For example, Kanpur’s leather units have got severely affected by the use of polluted water of the Ganga and any other river. Similarly, polluted water affect manufacturing in gujrat, maharashtra, west bengal and other states
  • Contamination of water bodies
    Water pollution affects all water bodies such as lakes, rivers, oceans, and groundwater, definitely human activities are responsible for these conditions. Making self-interest their priority, man avoid various established laws and regulations and drains various harmful substances coming out from the factories out-rightly into the water sources.
    The harmful elements found in industrial waste involve chemicals, grease, oil, paint, iron, cadmium, lead, arsenic, zinc, etc. It has also been observed that some industry drain radio-active substances into the water sources which destroy organisms and plants instantly and are extremely harmful. The Ministry of Environment and Forest has marked some industries which are polluting the water bodies very much. These are wine industry, skin purifier industry, petrochemical, paper industry, fertilizer industry, pharmaceutical industry, and sugar industry.
  • Effects on day-to-day life
    The nature of polluted water is acidic that why it damages the structure of the pot in which it is contained which results in interruptions in water storage. Alkaline substances mixed in polluted water get collected in and around taps making them undermine.
  • Invasive species
    Plants of water hyacinth are considered the world’s most problematic aquatic weed, called ‘Terror of Bengal’. They grow in eutrophic water bodies and lead to an imbalance in the ecosystem dynamics of the water body. They cause destruction by their excessive growth leading to stagnation of polluted water.

Dissolved Oxygen (DO)

Presence of organic and inorganic wastes in water alleviates the dissolved oxygen content of the water. A number of factors like surface turbulence, photosynthetic activity, O2 consumption by organisms and decomposition of organic matter are the factors which determine the amount of DO present in water. The higher amounts of waste increase the rates of decomposition and O2 consumption thereby decreases the DO content of water.

Biological Oxygen Demand (BOD)

Water pollution by organic wastes is measured in terms of Biochemical Oxygen Demand (BOD). BOD is the amount of dissolved oxygen required by bacteria in decomposing the organic wastes present in water. It is expressed in milligrams of oxygen per litre of water. The higher value of BOD indicates low DO content of water. Since BOD is restricted to biodegradable materials, it is not the right method of measuring water pollution.

Chemical oxygen demand (COD)

Chemical oxygen demand (COD) is a moderately better mode used to measure pollution load in the water. COD also measures the amount of oxygen in parts per million needed to oxidise organic (biodegradable and non-biodegradable) and oxidizable inorganic compounds in the water sample.


In this process, Lakes receive their water from surface runoff and along with its various minerals and chemical substances. Over time there is the accumulation of mineral and organic matter and slowly, get filled up water bodies. The nutrient-enrichment of the lakes boosts the growth of algae, aquatic plants and various fauna. This process is known as natural eutrophication. Similar nutrient enrichment of lakes at an accelerated rate is the result of human activities and the consequent ageing phenomenon is called cultural eutrophication.

On the basis of their nutrient content, lakes are categorized as

  • Oligotrophic (very low nutrients)
  • Mesotrophic (moderate nutrients)
  • Eutrophic (highly nutrient rich).

A vast majority of lakes in India are either mesotrophic or eutrophic because of the nutrients formed from their surroundings or organic wastes entering them.

Eutrophication and Algae Bloom

Eutrophic water body:

It is a body water rich in nutrients and so supporting a dense plant population, the decomposition of which terminates animal life by depriving it of oxygen. Eutrophication is the response to the addition of nutrients like phosphates and nitrates naturally or artificially, fertilising the aquatic ecosystem.
Phytoplankton (algae and blue-green bacteria) blooms on the redundant nutrients and their population explosion covers the entire surface layer and this condition is called "algae bloom".


Phytoplankton is photosynthetic during day time attaching oxygen to the aquatic ecosystem. But during nights, they consume far more oxygen as they respire aggressively. i.e. Algal blooms accentuate the rate of oxygen depletion as the population of phytoplankton is very high. The primary consumers such as small fish are terminated due to oxygen deprivation caused by algal blooms. Food chain is severely affected by the death of primary consumers. Further, microorganisms take more oxygen during the decomposition process of dead algae, fishes and plants. The new anaerobic conditions (absence of oxygen) built to enhance the growth of bacteria like Clostridium botulinum which releases toxins deadly to aquatic organisms, birds and mammals.

Diseases caused by pathogenic organisms in contaminated water

  • By Virus
    Jaundice (Yellow Fever), gastroenteritis, infectious liver Sod, common cold, polio, and smallpox.
  • By Bacteria
    Diarrhoea, loose motions, paratyphoid, high fever, cholera, whooping cough, gonorrhoea, syphilis, gastroenteritis, dysentery, and tuberculosis (related to lungs problem).
  • By Protozoa
    Pyorrhoea, dysentery, narcolepsy (epidemic encephalitis), malaria, amoebiasis, and giardiasis.
  • By Worm
    Filariasis, hydatid cyst and a different types of worm disease (various types of stomach worms).

In children, the surplus amount of nitrate leads to the disease methemoglobinemia and forms stomach cancer by reaching the intestine. "Fluorosis" is a disease caused by excess of fluorine. Excess level of mercury in fish is baneful especially for small children and pregnant women or nursing women. Gradually, it stops the development of young children and central nervous system present in the foetuses.

Measures to control Water Pollution

One should realize the importance of maintaining the cleanliness of the water bodies, the Government of India has passed the water (Prevention and Control of Pollution) Act, 1974 to shield our natural water resources. An ambitious plan to save the river called the Ganga Action Plan was launched in 1985 by our India's government. It aimed to diminish the pollution levels in the river, lakes and sea. Though, the increasing population and industrialization have already damaged this mighty river beyond repair. In India, the Central Pollution Control Board (CPCB), an apex body in the field of water quality management, has developed a concept of “designated best use”.

Accordingly, the water body is designated as A, B, C, D, E on the basis of:

For example pH, dissolved oxygen, mg/1 BOD, (200C) mg/l, total coliform (MPN/100ml), free ammonia mg/l, electrical conductivity, etc.

The famous Ganga Action Plan and subsequently the National River Action Plan are results of such exercise.

Riparian buffers

A riparian buffer is a vegetated area (a “buffer strip”) close to a stream, generally forested, which helps shade and partially shield a stream from the influence of adjacent land uses. It plays a vital role in increasing water quality in associated streams, lakes, and rivers, thus providing environmental benefits.
Treatment of sewage water and the industrial effluents before mixing up in water bodies. Hot water should be cooled before releasing from the power plants. Plethora use of pesticides and fertilizers must be ignored. Organic farming and efficient use of animal residues as fertilizers should replace chemical fertilizers. Water hyacinth (an aquatic weed, invasive species) purify water by taking out some toxic materials and ample of heavy metals from water. Oil spills in water can be cleaned with the help of bregoli — a by-product of paper industry resembling sawdust, oil zapper and microorganisms. It is suggested that we should plant eucalyptus trees all along sewage ponds because these trees can absorb all excessive wastewater rapidly and generate pure water vapor into the atmosphere.

Other measures for Control of pollution are:-

  • Municipal wastewater treatment
  • On-site sanitation and safely managed sanitation
  • Industrial and agricultural wastewater treatment
  • Erosion and sediment control from construction sites
  • Control of urban runoff (storm water)
  • spreading awareness among common people of the importance of water pollution and their harmful impact

At present, we are not only facing water pollution problem but also facing water scarcity crisis. So, we should pay attention on all aspects of water safety, need to protect, secure and conserve water resources. We should focus on water harvesting and preservation, along with reducing the wastage of water. Water pollution influences atmosphere around us, even decrease the life of the earth. We all contribute to water pollution whether knowingly or unknowingly. It is very important to have days where every single person can take part in cleaning the water bodies. These steps would not only protect the marine life but also reduce the chances of getting water borne diseases.