What are the effects of water pollution?

Water covers over 70 per cent of the Earth's surface and is the foundation of life, essential for our survival and the health of ecosystems. It sustains aquatic life, supports diverse habitats and is vital for all living beings.

Understanding the causes and effects of water pollution is therefore crucial for preserving our planet's most valuable resource.

What is water pollution?

Water pollution occurs when contaminants enter water bodies such as oceans, lakes, rivers, groundwater and aquifers, either directly or indirectly. These pollutants can originate from various sources and significantly harm ecosystems, wildlife and human health. It is the second most prevalent type of environmental pollution, following air pollution.

Below, we'll explore the different types of water pollution and their impacts.

Types of water pollution

Water contamination is categorised based on the source of the pollutant or the nature of the water body it affects. Some of the most common pollution types are:

Surface water pollution

Surface water includes water that is found naturally on the earth's surface, such as lagoons, rivers, oceans and lakes. Contamination of these water bodies happens when pollutants dissolve in or mix with the water.

This pollution can be accidental, like oil spills in the ocean, or intentional, such as industries discharging waste into rivers or seas. Both forms of pollution have significant impacts on the environment, wildlife and human communities.

Groundwater pollution

Groundwater pollution occurs when hazardous chemicals and particles applied on the surface by humans seep into the ground through rainwater. These contaminants then pollute underground water sources such as underground rivers and waterbeds.

As a result, wells and boreholes may become contaminated. The most common cause of this type of pollution is the use of pesticides and fertilisers on farms.

Chemical pollution

Chemicals are the most common type of water contaminants, affecting both surface and underground water bodies. Industrial, commercial and farming activities are the leading causes of this pollution.

Solvents and metals used in industries can pollute rivers and lakes. On farms, pesticides used to control weeds, insects and fungi contribute to soil contamination. Chemical contamination also occurs due to petroleum spills.

Nutrients pollution

Even though nutrients are essential for plant and aquatic life, an excess of them can be harmful. Wastewater and fertilisers contain high levels of nutrients needed for plant growth. When these nutrients enter water bodies, they can cause rapid and uncontrolled growth of vegetation and algae on the water surface.

This in turn leads to the clogging of water filters and contamination of drinking water. It also uses up oxygen, leading to the destruction of marine life.

Eutrophication

Eutrophication is a process that occurs when an excess of plant nutrients, such as phosphorus and nitrogen, accumulate in waterways. This can lead to algal blooms - dense growths of algae that block sunlight from entering the water and deplete oxygen levels, resulting in fish kills.

While some algal blooms can be beneficial for ecosystems, they can also be toxic and harmful to the environment.

Oxygen depletion pollution

Aquatic microorganisms thrive on biodegradable substances, and when large amounts of these materials enter the water, the population of microorganisms increases.

They consume all the oxygen in the water, leading to oxygen depletion, which causes the death of aerobic microorganisms but allows anaerobic organisms to thrive.

Some anaerobic microorganisms contaminate the water by producing toxins such as sulfides and ammonia, which are harmful to both humans and aquatic life.

Microbiological pollution

Microbiological pollution is a natural form of water contamination caused by naturally occurring microorganisms such as protozoa, viruses and bacteria.

Water containing these microorganisms can lead to diseases such as cholera and bilharzia.

The effects of microbiological pollution are particularly common in areas where people rely on untreated water for drinking, making it a significant health concern in those regions.

Suspended matter

Some contaminants do not dissolve in water and are too large to mix with water molecules. These include items like cans, straws and other large objects. When suspended, they form a layer on the water's surface, blocking oxygen penetration and leading to oxygen depletion pollution.

Some particulate matter may settle at the bottom of a lake, ocean or river, impacting the life that exists on the floor of these bodies of water. In some cases, these materials can also contain harmful toxins, further affecting the aquatic ecosystem.

Effects of water pollution

Water pollution affects both humans and aquatic life. Many water sources near cities and urban centres are contaminated by garbage and chemical dumping, whether legally or illegally.

Below are some of the most common and severe effects of polluting water bodies.

Effects on human beings

Life is a cycle, and humanity's negligent behaviour often returns to haunt it. Polluting water bodies has significantly impacted human health and the environment.

According to a 2023 UN World Water Development report, 2 billion people, or 26 per cent of the global population, lack access to safe drinking water, and 3.6 billion people, or 46 per cent, do not have access to safely managed sanitation services.

One of the most severe consequences of this is the spread of diseases. In a 2023 assessment, the World Health Organization identified between 21,000 to 143,000 cholera-related deaths worldwide, estimating that there are 1.3 to 4.0 million cases of cholera globally each year.

Additionally, events like the Fukushima disaster have led to long-term health consequences, with studies showing a 70 per cent rise in thyroid cancer among infants exposed to radiation.

Decimation of aquatic life

Animals and plants that rely on water for survival are the most impacted by water pollution.

Statistics from the Centre for Biological Diversity on the effects of the Deepwater Horizon spill offer a stark illustration of this impact. The 2010 spill in the Gulf of Mexico harmed over 82,000 birds, 25,900 marine animals, 6,165 sea turtles and an uncounted number of fish and invertebrates.

Food chain disruption

Pollution disrupts the food chain by transferring toxins from one level to higher levels. In some cases, it can wipe out an entire part of the food chain, causing further imbalances.

For instance, if a predator dies, it may lead to excessive growth in prey populations, while the loss of prey can result in the decline of predators.

Economic effects

Managing and restoring polluted water bodies is an expensive endeavour. For instance, Japan declared in 2019 that it is running out of space to store the contaminated water from the Fukushima disaster, with over a million tonnes stored in tanks.

Research indicates that cleaning up the effects of the disaster will cost at least USD 660 billion.

Even under normal conditions, the cost of purifying drinking water is high, not to mention the health expenses associated with treating diseases caused by contaminated water.

Protecting water bodies

Water is an essential natural resource vital for the survival of all living things. Any reckless actions by humanity negatively impact all other beneficiaries of this resource.

It is therefore crucial to protect water bodies from deliberate pollution to ensure the health and sustainability of ecosystems and communities that depend on them.