28, Oct 2023
Causes and Effects of Water Pollution: Chemicals, Oil Spills, Rising Temperatures, and Deforestation

Causes and Effects of Water Pollution

Water pollution occurs when anthropogenic (human-related) contaminants enter freshwater ecosystems in quantities that degrade the quality of water for any intended use. The contaminants may be chemical, biological or even thermal.

The most common pollutants include faecal waste, pharmaceutical chemicals, fertilisers, pesticides, plastics, nitrates and phosphates. Rising temperatures due to global warming are also considered a form of water pollution.

Chemicals and Pesticides

Using chemicals and pesticides in farming is a major cause of water pollution. The pesticides can seep into the ground water and surface water systems that eventually feed into drinking water supplies. Some of these pesticides have been linked to certain health problems in humans.

Pesticides and fertilizers enter the waterways through runoff, spills and improper disposal. They contaminate rivers, lakes and oceans, harming the ecosystem. Small aquatic creatures known as invertebrates are most affected by the chemicals. The deaths of these animals can have a large impact on the larger organisms in the ecosystem.

Most of us assume that soil acts as a filter and prevents pesticides from reaching groundwater, but this is not always the case. Some chemicals, like DDT and lead hydrogen arsenate, contain fluoride, chlorine and other toxic elements that don’t break down easily. The majority of drinking water is sourced from groundwater. The concentrations of these contaminants are increasing in some areas.

Oil Spills

Oil spills from tankers, refineries, drilling rigs and ports pollute the ocean. They can be caused by accidents from people making mistakes or being careless, by terrorists, countries at war, vandals and illegal dumpers.

Although small oil spills can cause localised damage, big ones are catastrophic to marine life. They suffocate fish, get caught in the feathers of birds stopping them from flying and block the light from photosynthetic aquatic plants.

Even when a big oil spill is cleaned up, it can contaminate beaches and sediment that will take years to recover. It can also seep into rivers and lakes that are naturally connected to the ocean and contaminate clean water supplies that people and animals need to survive. It can particularly affect poverty ridden countries where clean water is scarce as it can make their water unusable.

Rising Temperatures

The rising global temperatures caused by the burning of fossil fuels heat the water, reducing its ability to hold dissolved oxygen. Oxygen-depleted waters provide fertile environments for the proliferation of algae, which causes a phenomenon known as eutrophication.

In addition, sewage from factories and fracking sites finds its way into rivers, lakes and seas. Chemical dumping from these industries and the erosion of forests that are replaced by industrial activity also contribute to water pollution.

Every year, contaminated water makes around a billion people unwell with diseases such as cholera, giardia and typhoid fever. In developing countries, lack of education and poverty prevent people from taking care of their health and avoiding infections from pathogens in polluted water.


Forests play a crucial role in water quality and availability. Their roots help absorb rainfall and prevent excessive runoff, reducing the likelihood of flooding and pollution. Deforestation, which is often done to make way for farms or to create space for industrial development, reduces the amount of groundwater available and leads to water scarcity, affecting human communities.

The loss of trees also increases the risk of soil erosion. Without the plants’ roots to hold the soil in place, rain can wash sediment into rivers, lakes, and streams, reducing water quality and causing flooding.

In addition, forests are home to many species of animals and plants that contribute to the ecosystem’s biodiversity. When these species lose their habitats, it can lead to extinction, which further disrupts the ecosystem’s dynamics and affects the quality of water. Forests are also important for storing carbon, which is lost when they are cleared. These environmental issues can be addressed through awareness and education campaigns, incentivizing sustainable practices, and strict penalties for illegal deforestation.

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