Water Pollution

Water Pollution

This article deals with ‘Water Pollution – UPSC.’ This is part of our series on ‘Environment’ which is an important pillar of the GS-3 syllabus. For more articles on Science and technology, you can click here


Water pollution occurs when there is a change in the chemical, physical or biological quality of water that has a harmful effect(s) on living organisms that consume it or live in it.

When is water said to be polluted?

  • When it is impaired by contaminants 
  • Doesn’t support human use like drinking
  • Undergoes a marked shift in the ability to support its constituent biotic communities like fish (For example, almost all the fishes in Ulsoor Lake (Bangalore) died due to water pollution)

Sources of Water Pollution

There are two main types of sources: point sources and non-point sources 

1. Point sources

  • Contaminants that enter a waterway from a single and identifiable source.
  • Examples: from a sewage plant, a factory etc. 

2. Non-Point Sources

  • Non-Point Sources are the sources of water pollution that cannot be traced to a single source.
  • For Example, Acid rain, chemical runoff, and leaching out of nitrogen compounds from fertilized agricultural lands.

Apart from that, Groundwater aquifers are susceptible to contamination from sources that may not directly affect surface water bodies. E.g., chemical spill into the soil may not pollute any surface water body but pollute the underground water aquifer.

Causes of water pollution 

Water Pollution

1. Agricultural

  • Agricultural wastes include fertilizer and pesticide runoff from agricultural fields, food processing waste, tree and sawdust from logging operations and sewage from livestock operations.

2. Industrial Sector

  • Industrial discharge (effluents) may contain various compounds such as heavy metals (cadmium, chromium, lead) and organic and inorganic chemicals. These discharges can affect the temperatures of the water bodies and dissolved oxygen levels.

3. Domestic/Municipal Sector

  • The majority of domestic waste generation makes sewage which is dumped into water bodies without treatment. 

4. Thermal Pollution

  • When water at elevated levels of temperature used to run turbines in Power plants is discharged into rivers, streams or oceans, it increases the temperature of the water body. Also, it decreases dissolved oxygen in the water, which adversely affects aquatic life.

Why should India be worried about Water Pollution?

  • India should worry because India is already a water-deficient country. India has almost 18 % of the global population but only 4 % of freshwater.
  • Just 8% of domestic and industrial wastewater is released into the environment after treatment. It pollutes the natural waterbodies, making them unfit for human consumption.
  • The phenomenon of global warming has modified the ecology of major rivers of India. For instance, Ganga and Indus suffer significant-to-severe levels of water scarcity for 7 to 11 months in a year. 

Measurement of Water Pollution

1. Physical Testing

Standard physical tests of water include 

  1. Temperature
  2. Solid concentrations (e.g. Total Suspended Solids (TSS))
  3. Turbidity

2. Chemical Testing

Water samples may be examined using the principles of analytical chemistry. Frequently used methods include 

  • pH
  • Biochemical Oxygen Demand (BOD): It measures oxygen used by micro-organisms in the oxidation of organic matter. 
  • Chemical Oxygen Demand(COD): It measures oxygen equivalent to the oxidation of total organic matter present in water.
  • Metals (like cadmium and lead), oil & grease and pesticides.

3. Biological Testing

  • Involves the use of the plant, animal, and microbial indicators to monitor the health of an aquatic ecosystem. 
  • Example: Copepods 

Effects of water pollution

Water pollution strongly impacts humans, animals, vegetation, and the entire ecosystem. These effects can be classified into

On Ecosystem

  1. When sewage water and agriculture runoff containing organic material is discharged into freshwater, it increases the growth of algae, causing eutrophication and death of the whole aquatic ecosystem.
  2. If warm water is disposed of in coastal areas containing corals, it leads to the destruction of the whole ecosystem.
  3. A steep increase in Biological Oxygen Demand turns the lake or sea into a dead zone, killing all the organisms in the ecosystem.

On Animal Health

  1. Fishes and aquatic animals are poisoned by the dumping of industrial wastes in water bodies. 
  2. Oil spills kill a number of animals in the affected area.
  3. It leads to bioaccumulation and biomagnification across various trophic levels.

On Human Health

  1. Humans suffer from diseases like hepatitis by eating seafood contaminated due to water pollution.
  2. Heavy metal poisoning of the fishes due to water pollution can cause diseases in humans. E.g., Minamata disease due to mercury poisoning impacted humans as well.
  3. Consumption of polluted water results in cholera and typhoid.
  4. Nitrate contamination of water can prove to be disastrous for infants as it can restrict the oxygen to reach the brain causing the ‘blue baby syndrome.

Control of water pollution

Control of Domestic Sewage

  • It can be treated in urban areas by centralized sewage treatment plants.

Control of Industrial wastewater

  • Industrial waste can be treated with the help of Common Effluent Treatment Plants (CETP) in industrial areas.

Control of agriculture wastewater

  • Farmers may utilize erosion controls to reduce runoff flows and retain soil on their fields. ‘
  • Farmers should use nutrient management plans to prevent the application of excess nutrients. 

3R Approach to manage wastewater

Government, organizations and individuals can adopt the ‘3R Approach’ to reduce wastewater which includes  

  1. Reduce (water wastage)
  2. Reuse (after treatment)  
  3. Recycle
3R Approach to manage wastewater

World Examples

  • In Singapore and  San Diego, residents already drink recycled water. 
  • Japan’s sewage operators use bio-solids as a carbon-neutral form of energy.

Side Topic: Waterman of India (Rajendra Singh)

  • Rajendra Singh is India’s noted environmentalist and is nicknamed the “Waterman of India” Rajendra Singh
  • He was awarded the Stockholm Water Prize in 2015 and Magsaysay Award in 2001 for community-based water management.
  • He was born in UP but worked in Rajasthan for decades to solve the drought issue in Indian villages. 
  • He runs the “Jal Jan Jodo” campaign to spread the water conservation message.
  • He is the proponent of community-based water management as the best way to manage water. 

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