24, Sep 2023
Contaminated Water Threatens Ecosystems and Human Health

Water Pollution Overview

Water pollution is when lakes, rivers, oceans, aquifers, groundwater or the sea become polluted with contaminants. This can harm the ecosystem and humans who rely on that ecosystem to survive.

Water is a universal solvent and dissolves a lot of chemicals that are harmful to living things. This includes bacteria and viruses that cause diseases like diarrhoea.


Sewage is water that moves away from people’s houses after they wash dishes, do laundry and use toilets. It is also known as wastewater and it contains a wide range of organic and inorganic waste materials including disease-causing bacteria, viruses and parasites.

Besides sewage, wastewater may contain other pollutants like heavy metals which are difficult to remove with biological treatment. It also includes nutrients like nitrogen and phosphorus which encourage the growth of algae and water hyacinth in water bodies depleting oxygen. This deprives fish and other aquatic life of oxygen leading to their deaths. This water contaminated with these harmful organisms emits foul odours.

Careless people often use their toilets to deposit paper, sanitary products and even plastics into sewer systems. These waste materials clog sewer ways which leads to a lack of flow in the system. This halts the sewage treatment process leading to contamination of nearby water bodies with bacteria and other harmful organisms.


Oil pollution causes immediate and long-term damage to waterways and the wildlife that depends on them. Its sludgy consistency suffocates marine life and blocks sunlight from penetrating the ocean’s surface, killing ocean plants that rely on photosynthesis for survival. It also contaminates freshwater lakes, rivers and coastal wetlands.

In addition to big spills from disabled tankers and oil drilling platforms at sea, leaking pipes and regular operations of port facilities contribute to oil pollution. But the bulk of the world’s oil pollution comes from land sources, including waste oil and gasoline that drip from millions of cars each day.

The use of pesticides is another leading cause of water contamination. In a 2021 Mongabay investigation, we found that outdated pollution-control technology in some fertiliser plants in the US allows them to dump nitrogen (which triggers algae blooms and leads to fish-killing “dead zones”) into nearby waterways. This can contaminate drinking water, harming human and animal health.


The use of pesticides contaminates water and causes health problems for humans. This is especially dangerous when the chemicals get into groundwater. The chemicals can also contaminate other areas, including lakes and rivers.

The most common way that pesticides contaminate water is through runoff. This can be from agricultural fields, sewage treatment plants, and chemical spills.

Once in the water, pesticides can damage fish, animals, and plants. The chemical chlorpyrifos, for example, has caused fish kills in many streams. It can also damage non-target plants, and it is very toxic to insects.

The most common pesticides that contaminate water are the organophosphorus compounds, which are very soluble in water. These are commonly used in agriculture. Other pesticides, like the chlorinated hydrocarbons that were used before World War II, are less soluble and have a tendency to stay in soil particles. They rarely contaminate groundwater. However, the synthetic organic pesticides that replaced them tend to infiltrate more easily into groundwater.

Global Warming

There are many different types of water pollution, but the main cause is human activity. The pollutants can be anything from pathogenic microorganisms to chemical substances or waste. They can be found in any body of water, including rivers, lakes, oceans and aquifers. The pollutants can be harmful to humans, animals and plants.

Every year, around a billion people are sickened by drinking polluted water. This is because of harmful pathogens, like cholera and giardia. Nutrient pollution from fertilizer runoff and sewage discharge are also big problems. This type of pollution can also lead to algal blooms, which are a toxic soup of blue-green algae.

The climate crisis is causing more and more problems with water quality. Rising temperatures kill water-dwelling animals, contaminate waters and alter ecosystems. Severe weather events such as floods and droughts affect water supplies. This has become a major concern for the world and is one of the goals that the United Nations is trying to achieve with their Sustainable Development Goals.

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