Water pollution is a change in the composition and quality of water that cannot be met for different uses, exceeds the permissible standard and has a negative impact on the life, health of people and organisms.

Water in nature exists in many different forms: sewage water, water in rivers and lakes, exist as vapor in the air. Contaminated water means that its constituents exist with other substances, which can be harmful to humans and the lives of organisms in nature. Polluted water is often difficult to overcome, but must be prevented from the start.

In the process of daily life, under the current growth rate, people accidentally pollute water sources with chemicals and wastes from factories and factories. The individual units use groundwater in the form of drilling wells, after stopping the use, they do not seal the boreholes, causing dirty water to flow into and pollute the groundwater source. Factory and factory discharge industrial dust and dust into the air, pollute the air, when it rains, these pollutants will mix into the rainwater, also contribute to water pollution.

The European Charter on water has defined: "Water pollution is a generally human transformation to water quality, contaminating the water and endangering people, industry, agriculture, and animals. domestic animals and wild species. "

Water pollution is of natural origin: rain, snow melts, storms, floods introduce dirty wastes and harmful organisms, including their corpses, into the water environment.
Water pollution of artificial origin: the process of discharging toxic substances mainly in liquid form such as domestic, industrial, agricultural and transport wastes into the water environment.
According to the nature of pollutants, water pollution types are classified: organic pollution, chemical pollution, biological pollution, and physical pollution.
Saltwater pollution, groundwater and marine pollution.
Water pollution is a change in the direction of worsening the physical - chemical - biological properties of water, with the presence of foreign substances in liquid and solid form making water toxic to humans and biology. object. Reduce local biodiversity. In terms of the speed of transmission and the scale of impacts, water pollution is a more worrying issue than soil pollution.

Water pollution occurs when surface water flows through domestic waste, industrial waste water, and pollutants on the ground, and then seeps into the groundwater. Water pollution occurs when harmful chemicals, pathogenic bacteria, viruses, and parasites arise from different waste sources such as industrial wastes from manufacturing factories, and various types of waste. Hospital wastes, normal human wastes or chemicals, pesticides, organic fertilizers ... used in agricultural production are discharged into ponds, lakes, rivers and streams. or soak into groundwater without treatment or in excessively large volumes that exceed the self-adjusting and self-cleaning capabilities of ponds, lakes, rivers and streams.

Source
Polluted water is caused by cover that occurs mainly in freshwater areas, in coastal areas, and in enclosed seas. Due to the excess amount of mineral salts and organic matter content, the biomes in the water cannot be assimilated. As a result, the oxygen content in the water decreases dramatically, toxic gases increase, increasing turbidity of the water, causing degradation of the water body.

Natural pollution
Due to weather phenomena (rain, flood, wind storm, ...) or by products of living activities of organisms, including their corpses. Plants, organisms die, they are broken down by microorganisms into organic matter. A part will seep into the ground, then deep into groundwater, pollute or follow groundwater flows into large currents. Flooding can cause water to lose its purity, stir up impurities in the sewer system, carry a lot of hazardous waste from the dumping site, and take in chemicals previously stored. Floodwater can be contaminated by chemicals used in agriculture, industry, or by toxic agents in the landfill sites. Cleanup workers in the vicinity of flooded industrial sites can be harmed by contaminated water. Water pollution caused by natural factors (volcanoes, erosion, storms, floods, ...) can be very serious, but infrequently, and is not a major cause of global water quality degradation. .

Artificial pollution
From living
Domestic wastewater (Sewage): is wastewater generated from households, hospitals, hotels, schools, and contains wastes during human activities and sanitation. The basic components of domestic wastewater are biodegradable organic substances (carbohydrates, proteins, fats), nutrients (phosphorus, nitrogen), solids and bacteria. Depending on the standard of living and lifestyle, the amount of wastewater as well as the amount of substances in the wastewater of each person in a day is different. In general, the higher the standard of living, the higher the amount of wastewater and the discharge load.

From industrial wastes
Industrial wastewater: means the wastewater from public production facilities