The speed of industrialization and urbanization is quite fast and the population growth has put increasing pressure on water resources in the territory. The water environment in many urban areas, industrial zones and craft villages is increasingly polluted by wastewater, emissions and solid waste. In large cities, a large proportion of domestic waste is an important cause of water pollution. Water pollution due to industrial production is very heavy.

For example, in the textile industry, the pulp and paper industry, wastewater often has an average pH of 9-11, biochemical oxygen demand index (BOD), chemical oxygen demand (COD). can be up to 700mg / 1 and 2,500mg / 1, the content of suspended solids ... is much higher than the permitted limit. The waste content of these industries containing cyanide (CN-) exceeds 84 times, H2S exceeds 4.2 times, the concentration of NH3 exceeds 84 times the permitted standard, causing heavy pollution to the surface water sources. residential area.

There are many objective and subjective causes leading to water pollution

Water pollution in urban areas, waste water, domestic waste does not have a centralized treatment system but directly discharges into receiving sources (rivers, lakes, canals and ditches). On the other hand, many manufacturing facilities do not treat wastewater, most hospitals and large medical facilities do not have a wastewater treatment system, a large amount of solid waste in the city cannot be fully collected. ... are important sources of water pollution.

Regarding the pollution of water in rural areas and agricultural production areas, currently in our country, nearly 76% of the population is living in rural areas where the infrastructure is backward, most of the waste of untreated humans and livestock should be absorbed into the soil or washed away, making the pollution of the organic water and microorganisms increasingly high.

There are many objective and subjective reasons leading to water pollution such as: population growth, the reverse side of the process of industrialization and modernization, weak infrastructure, backwardness and receipt. People's awareness of environmental issues is not high ... Notably, the inadequacy in environmental management and protection activities. Awareness of many management agencies, organizations and individuals responsible for water environmental protection tasks is not deep and complete, it is unclear whether water pollution is a type of pollution that poses a direct danger. everyday and difficult to overcome human life as well as the sustainable development of the country.

The general consequence of water pollution is the rate of people suffering from acute and chronic diseases related to water pollution such as conjunctivitis, diarrhea, cancer ... increasing. People living around polluted areas are getting more and more suspected of using dirty water in every activity. In addition, water pollution also causes great losses to the production and business sectors and aquaculture households.

Scientific studies also show that when using arsenic-contaminated water to eat, people can get cancer in which the most common is skin cancer. In addition, arsenic also contaminates the circulatory system when drinking water sources with arsenic content of 0.1mg / l. Therefore, it is necessary to treat arsenic-contaminated water before using it for living and eating.

People with long-term lead can develop kidney and neurological diseases, infected with Ammonium, Nitrate, Nitrite causing blue-skin disease, anemia, can cause cancer. Methyl tert-butyl ether (MTBE) is a common additive in petroleum extraction, which is highly likely to cause cancer. Sodium (Na) infection causes high blood pressure, cardiovascular disease, sulfur causing disease in the gastrointestinal tract, Potassium, Cadimi causing spinal degeneration, back pain. Organic compounds, pesticides, insecticides, herbicides, growth stimulants, food preservatives, phosphorus ... cause poisoning, hepatitis, vomiting.

Long-term exposure will cause serious cancer of internal organs. Xenon peroxide bleaching agent, sodium percarbonate causing respiratory inflammation, oxalate combined with calcium to produce calcium oxalate causing kidney pain and gallstones. Bacteria, parasites of all kinds are the causes of gastrointestinal diseases, worms and parasites. Heavy metals: Titanium, Iron, lead, cadmium, arsenic, mercury, zinc cause neuropathy, kidney, excretory system, osteitis, anemia.