15 Main Causes of Water Pollution

In this blog post, we have outlined and discussed the main causes of water pollution. You can use this article as a guide or reference to your school essay or project related to water or general pollution.

Water being one of the environmental problems the world tries to mitigate today, let’s discuss the 15 main causes of water pollution.

WHO has been testing household water treatment products based on the WHO health-based performance requirement through the WHO International ‘Scheme’ to Evaluate Household Water Treatment Technologies since 2014.

Before we look at the 15 main causes of water pollution, let’s actually look at what water pollution is.

What Is Water Pollution?

According to the World Health Organisation (WHO), water pollution is when the composition of water has been changed to the extent that it is unusable.

Water pollution occurs when a body of water becomes contaminated, usually by chemicals or micro-organisms, degrading water quality and rendering it toxic to humans or the environment. Water pollution can cause water to become toxic to humans and the environment.

Water is an essential resource for all life on Earth. If a water source becomes contaminated due to pollution, it can lead to health issues in humans, such as cancer or cardiovascular conditions.

The main water pollutants include bacteria, viruses, parasites, fertilisers, pesticides, pharmaceutical products, nitrates, phosphates, plastics, faecal waste and even radioactive substances.

These substances do not always change the colour of the water, meaning that they are often invisible pollutants. That’s why small amounts of water and aquatic organisms are tested to determine water quality.

Effects Of Water Pollution

Having known the meaning of water pollution, we are now familiar with the term “water pollution”. Here are the effects of water pollution.

  • Contamination of the Food Chain
  • Lack of Potable Water
  • Infant Mortality
  • Diseases
  • Eutrophication
  • Death of Aquatic Life
  • Destruction of Ecosystems
  • Economic Effects

1. Contamination of the Food Chain

Pollution disrupts the food chain by moving the toxins from one level in the chain to higher levels. Disruption in food chains happens when toxins and pollutants in the water are consumed by aquatic animals (fish, shellfish, etc) which are then consumed by humans.

Fishing in polluted waters and the use of wastewater for livestock farming and agriculture can introduce toxins into foods that are harmful to our health when eaten. In some cases, pollution can wipe out an entire part of the food chain.

2. Lack of Potable Water

Water Pollution leads to a lack of potable water as the clean water for drinking has been polluted. The UN says that billions of people around the world have no access to clean water to drink or sanitation, particularly in rural areas.

3. Infant Mortality

According to the UN, diarrhoeal diseases linked to lack of hygiene caused the death of about 1,000 children a day worldwide.

4. Diseases

In humans, drinking or consuming polluted water in any way has many disastrous effects on our health. The WHO estimates that about 2 billion people have no option but to drink water contaminated by excrement, exposing them to diseases such as cholera, hepatitis A and dysentery.

Polluted water contains chemical toxins and a person who ingests chemical toxins in their water can be at risk of cancer, hormone disruption, altered brain function, damage to immune and reproductive systems, cardiovascular and kidney problems.

Swimming in contaminated water can trigger rashes, pink eye, respiratory infections, hepatitis, etc.

5. Eutrophication:

Chemicals in a water body, encourage the growth of algae. These algae form a layer on top of the pond or lake. Bacteria feed on this algae and this decreases the amount of oxygen in the water body, severely affecting the aquatic life there.

6. Death of Aquatic Life

Animals and plants that depend on water for life are the most affected by polluted water. Statistics from the Centre for Biological Diversity on the effects of the Deep Horizon spill provide a useful glimpse of the impact of pollution on aquatic life.

7. Destruction of Ecosystems

The introduction or elimination of certain micro-organisms distorts the ecosystem. Ecosystems are extremely dynamic and respond to even small changes in the environment.

Water pollution can cause an entire ecosystem to collapse if left unchecked.  Nutrient pollution, for example, leads to an increase in algae, which depletes the water of oxygen, thereby leading to the death of fish and other aquatic life. This also causes destruction in biodiversity.

8. Economic Effects

Managing and restoring polluted water bodies is expensive. For example, Japan declared in 2019 that it is running out of space to contain the contaminated water after the Fukushima disaster. It currently has over a million tons of contaminated water stored in tanks.

Research shows that it will cost at least $660 billion to clean up the effects of the disaster. In normal conditions, it costs more to purify drinking water, not to mention the health cost of treating diseases resulting from contaminated water.

15 Main Causes Of Water Pollution

Having known the meaning of water pollution and looked at the effects of water pollution, we want to look at the main causes of water pollution. Below is a list of the main causes of water pollution.

  • Industrial Waste
  • Global warming
  • Mining Activities
  • Urban Development
  • Leakage From the Landfills
  • Leakage From Sewer Lines
  • Accidental Oil Leakage
  • Underground Storage Leakage
  • Burning of fossil fuels
  • Radioactive Waste
  • Sewage and Wastewater
  • Agricultural Activities
  • Marine Dumping
  • Transportation
  • Construction activities

1. Industrial Waste

Industries produce a tremendous amount of waste and not having a proper waste management system they drain the waste in the freshwater, which goes into canals, rivers, and later into the sea.

This waste which is one of the main causes of water pollution contains harmful chemicals, including lead, mercury, sulfur, nitrates, asbestos, and many others causing water pollution and damage to our environment and us.

The toxic chemicals may change the color of water, increase the number of minerals, called eutrophication, change the temperature of the water, and pose a severe hazard to water organisms.

Big factories are notorious for dumping chemicals into the ocean. Highly toxic substances such as detergents, polychlorinated biphenyls, and lead are discharged into our environment every day causing water pollution.

2. Global warming

An increase in the earth’s temperature results in global warming due to the greenhouse effect is one of the main causes of water pollution.

Rising global temperatures caused by CO2 emissions heat the water, reducing its oxygen content resulting in the death of aquatic animals and marine species, which later results in water pollution.

3. Mining Activities

Mining activities are one of the main causes of water pollution as they involve crushing rocks that usually contain many trace metals and sulphides. These harmful chemicals can increase the number of toxic elements when mixed up with water causing water pollution which may result in health problems.

The leftover material from mining activities may easily generate sulfuric acid in the presence of precipitation water causing water pollution.

4. Urban Development

Massive urban development is one of the main causes of water pollution as anytime there are massive numbers of people conglomerated in one dense area, a physical disturbance of the land follows. As the population has grown exponentially, so has the demand for housing, food, and cloth.

As more cities and towns are developed, they have resulted in the increasing use of fertilizers to produce more food.

Soil erosion due to deforestation, rise in construction activities, inadequate sewer collection and treatment, landfills as more garbage is produced, increase in chemicals from industries to produce more materials.

The building of new roads, houses, and industries affects the cleanliness of the water through the use of detergents, chemicals, and exhaust emissions.

When it rains, these chemicals are washed into the rivers and streams, and eventually into the drinking water supply causing water pollution.

5. Leakage From the Landfills

Landfills which are one of the main causes of water pollution are nothing but a massive pile of garbage that produces an awful smell and can be seen across the city. When it rains, the landfills may leak, and the leaking landfills can pollute the groundwater below with a large variety of contaminants.

6. Leakage From Sewer Lines

A small leakage from the sewer lines can contaminate the groundwater and make it unfit for people to drink and the has been known to be one of the main causes of water pollution.

Leaking sewer lines may add trihalomethanes (such as chloroform) as well as other contaminants to the groundwater and when not repaired on time, the leaking water can come onto the surface and become a breeding ground for insects and mosquitoes.

Discharges of chlorinated solvents from dry-cleaners to sewer lines are also a recognized source of water pollution with these persistent and harmful solvents.

7. Accidental Oil Leakage

Oil spillage is one of the main causes of water pollution as oil spillage poses a huge threat to marine life when a large amount of oil spills into the sea and does not dissolve in water. It causes problems for local marine wildlife, including fish, birds, and sea otters.

A ship carrying a large quantity of oil may spill oil if met with an accident. Such an oil spill can cause varying damage to species in the ocean, depending on the amount of oil spill, the toxicity of pollutants, and the size of the ocean.

Oil leaks from vehicles and mechanic trades are another main cause of water pollution. The spilled oil mixes with groundwater and makes its way into streams and rivers causing water pollution.

8. Underground Storage Leakage

Underground storage leakage is one of the main causes of water pollution as the body of underground storage tanks like those used for storing petroleum products may rust as a result of old age or inferior materials used to build them

This causes the petroleum material being stored there to infiltrate the soil reaching the groundwater causing water pollution.

Also, the transportation of coal and other petroleum products through underground pipes is well known. Accidental leakage may happen anytime and may cause water pollution and also lead to soil erosion.

9. Burning 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 vapour result in acid rain which is one of the main causes of water pollution.

The emitted ash particles usually contain toxic metals (such as As or Pb). Burning will also add a series of oxides including carbon dioxide to the air which later leads to the pollution of the water bodies.

10. Radioactive Waste

Nuclear energy is produced using nuclear fission or fusion. The element that is used in the production of nuclear energy is Uranium, which is a highly toxic chemical.

The nuclear waste that is produced by radioactive material needs to be disposed of to prevent any nuclear accident. Nuclear waste is one of the main causes of water pollution as it causes serious environmental hazards if not disposed of properly.

Accidents have been known to occur, releasing horribly high amounts of harmful radioactive chemicals to be released into the air, water, and soil, and when released into water, it causes water pollution.

11. Sewage and Wastewater

Sewage and wastewater are one of the main causes of water pollution as the stage and wastewater that is produced in each household are treated chemically and released into the sea along with fresh water.

The sewage water carries pathogens, other harmful bacterias, and chemicals that pollute the water causing serious health problems and thereby diseases.

More and more, improper sewage disposal is becoming a major world issue as waste is being transported to a sewage treatment facility and from there, the remaining sewage is dumped into the oceans causing water pollution.

The WHO notes that, globally, around 2 billion people use a drinking water source with faecal contaminants (sewage and wastewater). Contaminated water can harbour bacteria, such as those responsible for diarrhoea, cholera, dysentery, typhoid, hepatitis A, and polio.

According to the UN, every year, approximately 297,000 children under five die from diseases linked to poor sanitation, poor hygiene, or unsafe drinking water.

12. Agricultural Activities

When it rains, runoff from farms carrying fertilizers, pesticides/insecticides/herbicides mixes up with rainwater and flow down into rivers and canals, which pose serious damages for aquatic animals  and other pollutants into water bodies such as lakes, rivers, ponds) leading to water pollution.

Chemical fertilizers and pesticides are one of the main causes of water pollution as these chemical fertilizers and pesticides are used by farmers to protect crops from insects and bacteria.

They are useful for the plant’s growth. However, the usual effect of this type of pollution consists of algae growing in affected water bodies.

This is a sign of increased nitrates and phosphates in water that could be harmful to human health. Chemical pollutants, such as pesticides, fertilizers, and heavy metals can cause serious health problems if ingested.

The result is dangerous algae blooms which eventually lead to the extinction of many underwater plants, as well as fish.

13. Marine Dumping

The garbage produced by households in the form of paper, plastic, food, aluminium, rubber, glass is one of the main causes of water pollution as these materials are collected and dumped into the sea in some countries causing water pollution.

Much of the plastic pollution in the ocean comes from fishing boats, tankers, and cargo shipping. Plastic materials/waste in contact with water degrade slowly releasing harmful compounds for both human health and the ecosystem.

When such things enter the sea, they not only cause water pollution but also harm animals in the sea.

14. Transportation

Transportation has since the introduction of mechanized vehicles been one of the main causes of water pollution.

In many countries, vehicle emissions usually contain Pb and this pollutes the air with various tailpipe compounds (including sulfur and nitrogen compounds, as well as carbon oxides) that may end up in water bodies via deposition with precipitation water causing water pollution.

15. Construction activities

Construction activities are one of the main causes of water pollution as construction works releases a number of contaminants into the ground that may eventually end up in groundwater through infiltration causing water pollution.

Foundries have direct emissions of metals (including Hg, Pb, Mn, Fe, Cr, and other metals) and other particulate matter into the air.


Minor Causes of Water Pollution

Some of the minor causes of water pollution are:

  • Sewage
  • Global warming
  • Oil leakage


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A passion-driven environmentalist by heart. Lead content writer at EnvironmentGo to educate the public on the environment and her concerns.
It has always been about nature, we ought to protect not destroy.

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