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Water Pollution, Meaning, Causes, Effects and Preventions

Water pollution

According to the definition of water pollution, it occurs when chemicals contaminate water sources, making the water unfit for swimming, cooking, cleaning, and other uses. Pollutants include things like chemicals, garbage, bacteria, and parasites, among others. All forms of pollution get up in the water eventually. Sewage discharges, industrial activities, agricultural practices, and urban runoff, which includes stormwater, are the four main causes of water pollution.

The Water Pollution is an important part of Environment and Ecology which an important subject in UPSC Syllabus. Students can also go for UPSC Mock Test to get more accuracy in their preparations.

Water Pollution Meaning

One of the most important natural resources on planet, water has existed for a very long period. . Actually, some form of the water we drink today has existed since the time of the dinosaurs.

More than two thirds of the earth’s surface is covered in water. This equates to just over 1 octillion liters, or 1,260,000,000,000,000,000,000 liters of water dispersed among the oceans, rivers, lakes, and streams. Even though there is a lot of water there, just 0.3% of it may be used for human use. As commercialization and industrialization have progressed, that number has decreased. Water contamination is also a result of ineffective and outmoded methods, ignorance, and a host of other factors.

Polluted water is defined by the World Health Organization (WHO) as water whose composition has been changed to the point where it cannot be used. To put it another way, it is tainted water that is unfit for essential tasks like agriculture and that transmits illnesses like cholera, dysentery, typhoid, and poliomyelitis, which result in the deaths of more than 500,000 people each year.

Bacteria, viruses, parasites, insecticides, medicines, plastics, excrement, radioactive materials, fertilizers, and pesticides are the main sources of water contamination. Since they don’t usually change the color of the water, these substances are frequently unseen contaminants. As a result, the water quality is determined by analyzing small samples of water and aquatic organisms.

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Water Pollution Causes

Sewage Water

Household and other establishment discharges are included in sewage water. Excreta from people and animals, leftover food, cleaning products, detergents, etc. are all found in the sewage. Hospital and domestic sewage are full of harmful pathogenic germs.

Dissolved Oxygen (DO)

Water’s dissolved oxygen level is decreased by the presence of organic and inorganic pollutants. Water that has a DO concentration less than 8.0 mg/L may be polluted. Water with a DO level of less than 4.0 mg/L is regarded as highly contaminated. The DO level of water is crucial for aquatic creatures to survive. The amount of DO in water is affected by a number of variables, including surface turbulence, photosynthetic activity, O2 consumption by organisms, and the breakdown of organic materials. Higher waste production speeds up decomposition and oxygen consumption, which lowers water’s DO level.

Biological Oxygen Demand (BOD)

Measured by biochemical oxygen demand, the volume of organic waste that contaminates water (BOD). BOD is the amount of dissolved oxygen that bacteria in water need to break down organic wastes. In milligrams of oxygen per liter of water, it is measured. Low DO level in the water is indicated by a higher BOD value. BOD is not an accurate way to measure water contamination because it can only be used with biodegradable compounds.

Chemical Oxygen Demand (COD)

A marginally more accurate method for determining the pollution load in water is chemical oxygen demand (COD). According to COD, the amount of oxygen needed to oxidize organic (both biodegradable and non-biodegradable) and oxidizable inorganic molecules in a water sample is measured in parts per million.

Industrial Wastes

Discharge of wastewater from industries such as oil and gas, paper production, metal extraction and processing, chemical manufacturing, etc in particular heavy metals (classified as elements with density > 5 g/cm3 such as mercury, cadmium, copper, lead, arsenic) and a variety of organic compounds, which commonly contain dangerous chemicals.

Marine Pollution

All pollutants, whether natural and man-made, are ultimately absorbed by the oceans. Additionally, the rubbish and sewage from coastal cities are dumped into the ocean. The navigational discharge of oil and grease; detergents, sewage, rubbish, and radioactive wastes; offshore oil mining; and oil spills are some of the additional sources of ocean pollution.

Oil Spills

Leakage during marine transport and leakage from underground storage tanks are the two most frequent causes of oil spills. Additionally, during offshore oil production, an oil spill could happen.

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Water Pollution Effect

Reduces the Level of Dissolved Oxygen

The amount of oxygen in water is known as dissolved oxygen, or DOES All forms of life depend on sufficient dissolved oxygen, which is necessary for high water quality. When organic and inorganic contaminants are present, the amount of dissolved oxygen in the water is decreased. These contaminants may be produced by industrial point sources, agricultural and urban runoff, and destruction of riparian vegetation, channel modification, and groundwater influx, among other factors.

Increases BOD

Biological oxygen demand is the quantity of oxygen needed by bacteria and other microorganisms while rotting organic matter in aerobic (oxygen present) conditions at a particular temperature (BOD). Bacteria require more oxygen the more organic contaminants there are in the water. As a result, the BOD and the quantity of pollution in a body of water are related.

Water will lose its oxygen content if too much pollution is introduced. Aquatic life that depends on oxygen perishes as a result. As a result, bacteria that don’t need oxygen (anaerobic bacteria) start to break down the organic waste, producing substances that are bad for people’s health and have a terrible odour.

As these organic wastes are broken down by aerobic (oxygen-requiring) bacteria, dissolved oxygen in the water will be depleted. Therefore, the amount of BOD in the water is a gauge of how much oxygen is necessary for the biological breakdown of the organic material. Consequently, BOD levels in the water increase when sewage and river water are combined.

Increases Chemical Oxygen Demand (COD)

The chemical oxygen requirement is the amount of oxygen needed to oxidise the organic matter in water. Cleansed wastewater may introduce organic material into the neighbouring waters if it is released into the environment. Organics in the wastewater are indicated by high COD levels, which can lower the amount of dissolved oxygen in the water and have a major environmental and regulatory impact.


Eutrophication is the term used to describe a rise in chemical nutrients in an environment, frequently compounds containing nitrogen or phosphorus. In addition to other detrimental effects including a lack of oxygen and drastic losses in water quality, fish populations, and other animal populations, it might result in an increase in primary productivity (excessive plant growth and deterioration).

The primary offenders are rivers that empty into the ocean, several chemicals used as fertilisers in agriculture, waste from livestock, and human garbage. An excess of oxygen-depleting chemicals in the water can lead to hypoxia and the creation of a dead zone.

Ocean Acidification

This happens when a variety of human activities cause carbon dioxide to be released into the atmosphere. As a result of the carbon gases dissolving in the ocean and reducing its pH and speeding acidification, the water gets contaminated. Along with other physiological issues for marine life, ocean acidification can reduce the production of calcium carbonate shells in shellfish and other aquatic life.

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Water Pollution & Effects

There are many harmful bacteria in domestic and medical waste, and dumping it into the water without proper treatment can cause an outbreak of cholera and typhoid, two devastating diseases. Humans and other animals are harmed by metals found in industrial wastewaters, including lead, zinc, arsenic, copper, mercury, and cadmium.

Arsenic builds up in bodily tissues like blood, nails, and hair after drinking arsenic-contaminated water, which leads to skin sores, rough skin, dry, thicker skin, and ultimately skin cancer. Mercury molecules in wastewater are changed by bacterial action into the very toxic methyl mercury, which can cause numbness in the limbs, lips, and tongue, hearing loss, distorted vision, and mental instability.

Mercury contamination of water sources causes Minamata in people (a neurological condition). Lead is what causes lead poisoning (Lead interferes with a variety of body processes and is toxic to many organs and tissues). Lead poisoning can cause anaemia, headaches, muscle weakness, and a bluish line around the gums. Itai itai disease, also known as ouch-ouch disease (a painful bone and joint disorder), as well as lung and liver cancer, can be brought on by cadmium-contaminated water.

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Water Pollution Preservation

Wastewater Treatment

Pollutants in wastewater are removed through a physical, chemical, or biological process during the wastewater treatment process. These techniques are increasingly successful as the water becomes cleaner.

Green Agriculture

It is vital to have climate-friendly crops, efficient irrigation that uses less water and energy-efficient food production because agriculture uses 70% of the fresh water in the globe. Green agriculture is also crucial to lowering the amount of contaminants that enter the water.

Storm Water Management

The US Environmental Protection Agency defines storm water management as “an effort to reduce the amount of precipitation or melted snow that is discharged into streets, lawns, and other sites while also improving water quality” (EPA). Because it increases the efficiency of water consumption, keeping pollutants out of the water is essential.

Air Pollution Prevention

Air pollution directly affects water contamination since the oceans absorb 25% of the CO2 emissions that people are responsible for. This pollution causes our seas to swiftly become more acidic, harming corals and other marine life. Preventing air pollution is the best way to prevent this from happening.

Plastic Waste Reduction

In our oceans, 80% of the plastic comes from land. If we want to reduce the amount of plastic entering our oceans, both the global consumption of plastic and the management of plastic waste must be improved.

Water Conservation

Without water conservation, humans will not advance very far. Enhancing worldwide access to clean water is crucial. It entails managing water appropriately and being aware that it is a limited resource.

Numerous techniques can be used to reduce water pollution on a bigger scale. It is preferable to treat sewage waste before release rather than discharging it into aquatic bodies. By doing this, the original toxicity can be reduced, and the water body itself can breakdown and render harmless any compounds that are still there. Water that has undergone secondary treatment may be used in sanitary systems and agricultural fields.

The Water Hyacinth is a very unique plant that has the ability to absorb harmful compounds in solution, including cadmium and other similar elements. Establishing these in areas vulnerable to these types of pollution will significantly lessen the negative consequences.

Precipitation, ion exchange, reverse osmosis, and coagulation are a few chemical techniques that aid in the management of water pollution. Reusing, reducing, and recycling whenever possible will go a long way toward overcoming the effects of water pollution on an individual basis.

Water Pollution UPSC

According to the definition of water pollution, it occurs when water sources are contaminated with contaminants that render the water unfit for swimming, cleaning, cooking, and other uses. Chemicals, garbage, bacteria, and parasites are examples of pollutants. Beyond surface water, groundwater, the ocean, and the sea have all been affected by water pollution. Students can read all the details related to UPSC by visiting the official website of StudyIQ UPSC Online Coaching.

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Water Pollution FAQs

What is sewage treatment?

Wastewater treatment or sewage treatment generally refers to the process of cleaning or removing all pollutants, treating wastewater and making it safe and suitable for drinking before releasing it into the environment.

What are the main steps in sewage treatment?

There are four main stages of the wastewater treatment process, namely:
• Stage 1: Screening
• Stage 2: Primary treatment
• Stage 3: Secondary treatment
• Stage 4: Final treatment

What are the main causes of water pollution?

The main causes of water pollution are attributed to
• Industrial activities
• Urbanization
• Religious and social practices
• Agricultural runoff
• Accidents (such as oil spills, nuclear fallouts etc)

What are the effects of water pollution?

Water pollution can have disastrous consequences on the ecosystem. Furthermore, toxic chemicals can travel through the food chain and get into our bodies, causing diseases and death.

When did water pollution start?

Along with amazing technological advances, the Industrial Revolution of the mid-19th century introduced new sources of air and water pollution. By the middle of the 20th century, the effects of these changes were beginning to be felt in countries around the world


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