Water pollution

The waters of the River Ganges flow clear and clean through the Indian city of Rishikesh at the gateway to the Himalayas. In these mountains, nobody would guess that this water will be transformed into one of the most heavily polluted rivers in the world, with faecal bacteria levels up to 31 million per 100 millilitres. This is according to reports from Sankat Mochan Foundation, an organisation struggling to restore the Ganges to its former glory. These levels mean that the sacred river has become synonymous with water pollution, a worldwide problem affecting one in every three people on the planet, according to the United Nations (UN).

What is water pollution?

The World Health Organization (WHO) defines polluted water as water whose composition has changed to the point that it becomes unusable. In other words, it is toxic water that can neither be consumed nor used for essential activities such as agriculture. It is also a source of poor sanitation that causes more than 500,000 deaths globally each year from diarrhoeal diseases and transmits illnesses such as cholera, dysentery, typhoid fever and polio. 

Depending on its source, there are different types of water pollution: chemical pollution, caused by pesticides, fertilisers and heavy metals that can cause disease when consumed; biological pollution, caused by bacteria, viruses and parasites originating from human and animal waste; physical pollution, resulting from the presence of plastics, sediments and waste that damage ecosystems; thermal pollution, caused by the discharge of hot water from factories into rivers and lakes, harming aquatic life; and microplastic pollution, which consists of plastic particles present in water and whose effects are still being investigated. 

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.

Emerging pollutants

Although plastic pollution in the oceans has long been a major concern, there are now many other contaminants affecting marine ecosystems. Microplastics, as mentioned above, represent a significant threat and are present in seas around the world. However, substances such as pharmaceutical residues also contaminate aquatic environments, primarily through urban and industrial wastewater, and conventional treatment processes do not always remove them completely. Among the most common emerging pollutants are compounds derived from narcotic substances, such as cocaine; agrochemicals, such as atrazine; personal care products, such as parabens; and substances from the food industry, such as caffeine. 

Why is water pollution such an important issue? 

Water pollution is one of the world's most urgent challenges. According to a study conducted by the WHO and UNICEF in 2025, around 2.1 billion people do not have safe access to drinking water, affecting not only health but also economic development. 

In most countries where data are available, women and girls bear the primary responsibility for collecting water in areas experiencing severe water stress. In regions such as sub-Saharan Africa and Central Asia, many spend more than 30 minutes each day on this task, limiting educational and professional opportunities and widening socioeconomic and gender inequalities. Furthermore, if the available water is contaminated, exposure to diseases such as cholera and hepatitis A makes this issue a serious threat to life. This risk is becoming increasingly common because, according to the UN, 80% of wastewater is discharged into the environment without treatment, meaning that much of the water consumed in developing countries contains highly toxic pollutants. 

The impact on food production is also direct. Agriculture depends on clean water to irrigate crops, maintain soil quality and support livestock production. If water contains contaminants or becomes scarce, yields decline, losses increase and both food prices and food security can be affected. 

In sectors such as energy, pollution also represents a major economic challenge. Power plants depend on large volumes of clean water for cooling systems. When available water is contaminated with sediments or organic matter, operational efficiency may decline and maintenance costs can rise significantly, affecting the cost of service.  

Cities also face growing financial pressures. Drinking water treatment and wastewater management require substantial investment in infrastructure, energy and maintenance. As pollution increases, municipalities must allocate more resources to maintaining reliable services, resulting in higher public expenditure and fewer resources for other priorities. 

For all these reasons, water pollution affects not only the environment but also everyday life, economic performance and social stability, ultimately limiting equal opportunities for people around the world.  

 SEE INFOGRAPHIC: The impact of water pollution [PDF] External link, opens in new window.

Responsible water management at Iberdrola 

At the Iberdrola Group, we undertake a wide range of initiatives to preserve and use water resources responsibly, making water management one of the key priorities within our corporate strategy. Our advanced treatment processes ensure that water returned to the environment meets – and often exceeds – the quality standards required by applicable regulations, minimising environmental impacts and supporting a cleaner and healthier water cycle. In addition, some of our facilities use recycled water in their operations, enabling more efficient and sustainable resource management 

Projects such as East Anglia ONE, where we supported the installation of two floating waste collection devices (known as seabins) to collect plastics and some of the oils, detergents and fuels floating near the port of Lowestoft, reflect our commitment to protecting marine environments. 

We also use water analysis tools to strengthen water risk management. This approach focuses on identifying, assessing and mitigating potential impacts and dependencies, helping to protect water resources while understanding how our operations may be affected by water availability and quality. These assessments enable us to develop effective strategies that reduce dependency and ensure operational continuity. 

In addition, we are working to advance a cleaner and more sustainable energy model. Electrification and decarbonisation are fundamental to reducing greenhouse gas emissions and achieving carbon neutrality, helping to protect our oceans, waterways and the natural environment.