Water is a vital resource for all life on Earth. However, human activities pollute it in various ways: domestic wastewater, untreated industrial water, plastic waste, leaks, and accidental spills, etc. All these sources of pollution threaten the availability of water and its quality for present and future generations.
Moreover, contaminated drinking water can cause diarrheal diseases, cholera, typhoid, and other serious health problems. Fish, plants, and other aquatic organisms are also direct victims. In this article, we will address the main water pollutants, as well as their origins.
Nitrates and phosphates, pollutants from chemical fertilizers
To grow, plants need food in the form of nutrients, two of which are essential: nitrogen and phosphorus. Nitrogen mainly comes from a complex cycle involving nitrates, nitrites, and ammonia.
Phosphorus, for its part, mainly comes from phosphates. It is found in rocks and minerals, but it is also released by human activity, particularly through the use of fertilizers and phosphate detergents.
Naturally, these elements are present in limited quantities, which hinders plant growth. However, to boost agricultural production, nitrogen fertilizers, livestock effluents, and other chemical substances are added to the soils. Rain then washes some of these nutrients into rivers and groundwater, enriching them with nitrates and phosphates.
This phenomenon promotes the proliferation of algae (eutrophication) that can invade waterways and lakes, depleting oxygen and threatening aquatic life. Dead algae and excess nutrients also make the water unsuitable for human consumption and irrigation.
In France, the maximum concentration of nitrates in drinking water is set at 50 mg/L. The concentration of phosphates is not regulated, but recommendations exist to limit their presence in tap water.
Organic materials, aquatic pollutants from living beings
An organic matter is a substance composed of carbon, hydrogen, and often oxygen, nitrogen, phosphorus, and other elements, coming from living beings or their residues.
What are the sources of water pollution by organic materials?
Water pollution by organic materials naturally comes from the decomposition of living organisms:
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dead leaves,
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branches,
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algae,
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animal waste, etc.
Untreated domestic and industrial wastewater from urban sewers also contributes to the pollution of aquatic environments, especially if there is no treatment plant. Excrement, food waste, hygiene products, and chemicals are pollutants that can contaminate water and harm aquatic life. Agricultural runoff, pesticides, and herbicides are not to be overlooked.
What are the consequences of the decomposition of organic materials in water?
Organic matter is an essential link in the carbon cycle, storing carbon and releasing it into the atmosphere as CO2. Its decomposition also releases nutrients (nitrogen, phosphorus) necessary for plant growth.
However, if the amount of organic matter in the environment is excessive, it can have negative impacts, such as the proliferation of algae. The decomposition of these materials in the water also consumes a lot of oxygen, causing the death of fish and other aquatic organisms.
An organic matter can even carry bacteria, viruses, and chemicals harmful to human health and aquatic wildlife.
Micropollutants, harmful substances in drinking water even at very low doses
A micropollutant is a chemical substance present in the environment at very low concentrations, often compared to a piece of sugar in an Olympic swimming pool. Despite their low quantity, micropollutants can have significant impacts on uses, ecosystems, the water network and public health.
How do micropollutants end up in the water?
The sources of groundwater pollution by micropollutants are varied, but most are of human origin:
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Industry: Manufacturing of plastics, detergents, solvents, petroleum products, etc.
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Agriculture: Pesticides, herbicides, fertilizers, etc.
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Domestic use: Cosmetics, paints, cleaning products, etc.
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Hospital activities: Pharmaceutical residues, contrast agents, hospital discharges, etc.
While there are nearly 100,000 micropollutant molecules today, creating a comprehensive list is an almost impossible challenge. Among them, PFAS and PCBs hold a prominent place due to their persistence to degradation.
Although PCBs have been banned in most countries since the 1970s due to their toxicity, they can still be found as contaminants in some older electrical equipment and industrial oils.
What are the health risks of micropollutants?
Even at low concentrations, micropollutants can have harmful effects on living organisms. For example, something as small as an alkylphenol can disrupt the endocrine system of living organisms. They can be found in:
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detergents,
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fuel additives and lubricants,
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fragrances,
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flame retardant materials,
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tires,
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coatings, etc.
Other micropollutants (parabens, PAHs, perfluorinated compounds, phthalates, medications) are also known to disrupt the hormonal system, leading to reproductive and developmental issues. Some substances, such as Volatile Organic Compounds (VOCs), are even classified as carcinogenic.
Heavy metals, pollutants from discharges into the environment
Heavy metals are natural metallic elements with a density greater than 5 g/cm³. Among the most common are:
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mercury,
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lead,
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cadmium,
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copper,
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arsenic,
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nickel,
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zinc,
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cobalt,
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manganese.
Where do heavy metals come from?
Heavy metals are naturally present in our environment, their origin being primarily rocks and soils. They can also be released by natural phenomena such as erosion or volcanic eruptions.
However, mining and metal production are the main sources of heavy metal emissions into the environment. Other human activities also contribute to this pollution, such as:
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the incineration of waste,
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the use of pesticides and fertilizers,
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the combustion of fossil fuels.
Why are there traces of heavy metals in tap water?
Water resource pollution most often occurs through industrial discharges, rainwater runoff, and erosion. Even after treatment of the water resource, there may be traces of metals affecting the quality of tap water. For example, the wear of lead pipes, once used in water distribution in cities, can release lead particles into drinking water.
Metal traces can have harmful effects on human health, depending on the type of metal, its concentration, and the duration of exposure. For example, mercury can cause damage to the nervous system, kidneys, and lungs. While lead can affect the brain development of children or cause learning and behavioral problems.
Waste, aquatic pollutants resulting from human activities
Human activities generate a considerable amount of waste of various nature and composition. Carried by water, wind, or deliberately discarded in nature, some of this waste ends up in aquatic environments, traversing watersheds at the mercy of currents.
What are the main types of waste that pollute water?
According to an alarming report fromEarthWatch Europe, more than 37% of the waste found in European waterways is made up of plastic from everyday consumer products.
Among these pollutants, plastic bottles (14%) and food packaging (12%) dominate, accounting for more than a quarter of the collected waste. Next are cigarette butts (9%), followed by takeout food containers, cotton swabs, and cups.
Under the action of natural elements (sun, water, frost, wind...), these plastic wastes fragment into increasingly smaller particles. Let us remember that the dangers of these microplastics are numerous. At the same time, some toxic substances present in their composition, sometimes referred to as micropollutants, dissolve in water, further contaminating the environment.
What are the risks associated with waste pollution?
Aside from the pollution of water intended for consumption, the proliferation of plastic waste in our waterways and oceans poses a major threat to the environment and biodiversity. They invade waterways, rivers, lakes, and seas, altering and destroying the natural habitats essential for aquatic fauna and flora.
Marine animals, often attracted by the appearance of plastic waste, ingest it, which can lead to digestive disorders, intestinal blockages, or even death. The ingestion of microplastics by humans, through the consumption of contaminated seafood or polluted drinking water, can also lead to health problems (inflammations and effects on the immune system).
Moreover, plastic waste introduces toxic substances into the ecosystem. They can absorb and concentrate pollutants present in water (pesticides, hydrocarbons, and heavy metals), thereby amplifying them in the food chain.
The European Parliament took an important step in 2019 by banning single-use plastics such as straws, cutlery, and cotton swabs, effective since 2021. At the same time, European legislation sets an ambitious target for member countries to collect 90% of plastic bottles by 2029.
Pathogenic microorganisms, invisible enemies using water as a means of transport
Unlike their non-pathogenic counterparts, these microscopic living beings are characterized by their ability to parasitize a higher organism, usually humans. They cause health disorders that can be more or less severe, and water serves only as a means of transport and contamination.
What are the common pathogenic microorganisms in rivers?
A wide variety of pathogens can be found in water to be treated, which requires various identification and elimination techniques. Among the most common are:
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bacteria,
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viruses,
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protozoa,
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fungi,
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worms,
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insects.
Most pathogens cannot survive long in water, but the duration varies by species. The sporulated or encysted forms, which are more resistant, persist longer.
Some viruses or bacteria can also be hosted by animals (reservoirs). Meanwhile, other worms have larvae that develop in aquatic intermediate hosts (mollusks, crustaceans, fish).
What are the main sources of water pollution by pathogens?
Discharges of domestic wastewater, livestock, or certain industries are the main sources of water contamination by fecal-origin pathogens. Wastewater treatment processes, whether collective or non-collective, aim to destroy enough pathogenic germs so that the final discharge no longer poses a health risk once diluted in aquatic environments.
In the absence of a treatment system or in case of its malfunction, the amount of pathogens released into the water can become dangerous to health. The most exposed individuals are those who swim or consume contaminated seafood (mussels and oysters).
In order to ensure the sanitary safety of drinking water, disinfection methods such as chlorination aim to eliminate or inactivate the pathogens present in raw water. Although the dangers of chlorine in drinking water are not negligible.
Frequently Asked Questions
Where does the water we drink come from?
The water we drink comes from two main sources: groundwater (aquifers) and surface water (rivers, lakes, glaciers, snowmelt). In France, 62% of drinking water comes from groundwater and 38% from surface water.
What activities create water pollution?
Water pollution mainly comes from the following activities:
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Domestic: Discharges of untreated wastewater (shower, laundry, dishes, etc.)
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Agricultural: Use of fertilizers and pesticides.
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Industrial: Discharges of effluents loaded with toxic chemicals, heavy metals, etc.
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Extractives: Mining, oil and gas drilling.
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Maritime transport: Discharge of ballast water, maritime accidents.
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Tourism and recreational activities: Discharge of waste into aquatic environments and beaches.
How to protect yourself from PFAS?
Start by informing yourself about the quality of your tap water through the dedicated page on the Ministry of Health's website. Some activated carbon filters can also reduce the concentration of PFAS in drinking water. Here is a detailed article on how to avoid PFAS.
Identify the main water pollutants to better protect your health
Although water is a vital resource for human health, its quality is alarmingly deteriorating due to pollution. Understanding the main water pollutants and adopting simple daily actions are essential to preserve your health and that of future generations.
Do you want to ensure access to clean and healthy water for your home? Then consider practical solutions like gravity-based activated carbon water filtration systems. Weeplow models can effectively reduce up to 99.999% of harmful contaminants in tap water.
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