Many human activities can negatively affect the water quality of rivers, lakes, oceans, and groundwater. Water quality is so-called “point source of water pollution” that is affected by direct inflows such as factories and wastewater treatment plants.
It is also affected by pollution from a wide range of sources, including nutrients and pesticides from agricultural activities and pollutants released into the atmosphere by industry. Pollutants return to land and sea. This is the so-called “diffuse pollution”.
The main source of water pollution is from sewage and waste water treatment, while the main sources of pollution are agriculture and fossil fuel power plants (through the air). Note that while wastewater treatment plants are identified as “point sources,” they are not true sources because they process what you put down toilets and sinks.
There are many sources for water pollution. Below we mention seven of the main factors of water pollution.
The Sources of Water Pollution
This section gives information about the most significant sources of water pollution.
Sewage (Waste Water)
Sewage is another name for wastewater from domestic and industrial processes. Harmful chemicals, bacteria, and pathogens can be found in wastewater and sewage, even if it is treated. Household sewage is dumped into the oceans along with fresh water.
Pathogens and bacteria present in that wastewater cause diseases and problems related to human and animal health. Despite strict regulatory controls, the water and wastewater industry accounted for almost a quarter of severe water problems in England and Wales in 2006, according to Environment Agency data.
The agricultural sector is not only the largest consumer of fresh water resources in the world, agriculture and animal production use about 70% of the surface water resources of the earth, but they are also a serious source of water pollution.
Around the world, agriculture is one of the main sources of water quality degradation. In the United States, agricultural pollution is the largest source of pollution in rivers, the second largest source of pollution in wetlands, and the third largest source of pollution in lakes.
It is also the main source of pollution of estuaries and underground water. Every time it rains, fertilizers, pesticides, and animal waste from farms and ranches carry nutrients and pathogens such as bacteria and viruses into waterways.
Nutrient pollution from excess nitrogen and phosphorus in the air is the biggest threat to water quality worldwide and can lead to algal blooms, toxic soups of blue-green algae that are harmful to humans and wildlife.
Industries and industrial sites around the world are the main sources of water pollution. Many industrial sites generate waste in the form of chemicals and toxic pollutants, and despite monitoring, some do not have a proper waste management system.
In these rare cases, industrial waste is dumped into nearby freshwater systems. If industrial waste is not treated properly (or worse, not treated at all), it can easily contaminate the freshwater systems it comes into contact with.
Industrial waste from farmland, mines, and manufacturing plants can end up in rivers, streams, and other water bodies that lead directly to the ocean. Toxic chemicals in the waste produced by these industries can not only make water unsafe for human consumption, but also alter the temperature of freshwater systems, making them dangerous for many aquatic organisms.
Each year, England and Wales have around 3,000 oil and fuel pollution incidents. Oil spills affect water quality in many ways. Oil may not be safe for drinking water. Large amounts of oil released into the seas and oceans destroy wildlife and the ecosystems that support them. Oil spills also reduce the supply of oxygen in the water environment. The main factors of water pollution caused by oil are:
- Losses caused by storage facilities.
- Spills during transportation.
- Planned disposal of waste oil in sewage systems.
Radioactive waste is any contamination that emits radiation beyond what is naturally emitted by the environment. It is produced by uranium mining, nuclear power plants, military weapons manufacturing and testing, and universities and hospitals that use radioactive materials for research and medical purposes.
Disposal is a major challenge because radioactive waste can remain in the environment for thousands of years. Consider the Hanford nuclear weapons production facility in Washington.
Here, cleanup of 56 million gallons of radioactive waste will cost more than $100 billion and is expected to continue through 2060. Accidental release or improper disposal of pollutants threatens groundwater, surface water and marine resources.
Many people throw supermarket trolleys, bicycles, garden clippings and e-waste into rivers and riverbanks. This is illegal and offenders may be prosecuted for fly swatting if caught. Dumping into rivers does not only cause water pollution. It also harms wildlife and increases the risk of flooding.
Reflecting flies (including spilling in rivers) is a crime. In the most serious cases, fines of up to £50,000 or five years in prison can be imposed.
Marine Dumping, as the name suggests, is dumping waste into the ocean. It may sound silly, but many countries around the world still collect household waste and throw it into the ocean. Most of these materials take 2 to 200 years to fully decompose.
The World-Wide Fund for Nature (WWF) estimates that a staggering amount of trash enters the ocean every year. Part of this is due to the deliberate dumping of waste in coastal waters. Other sources of litter in the sea include plastics and other materials blown up or washed ashore. Dumping at sea is illegal under international and UK law.