Pure water, clean water or pure water for short, is a pure, clean, do not contain impurities or bacteria in the water, in accord with hygienic standards for drinking water water as raw water, by electrodialysis method, ion exchange method, reverse osmosis, distillation and other appropriate, processing method, the seal in the container, and do not contain any additives, colorless, transparent, can be directly drinkable. The space water that sells on the market, distilled water belongs to pure water. Sometimes the word is also used with distilled water or rainwater from a chemical laboratory.

The metal element index stipulates the content of lead, arsenic and copper in the standard, and lead and arsenic shall not exceed 0.1mg/L, which mainly comes from the environment affected by human activities, including soil and river pollution. As lead, arsenic is poisonous and harmful elements, but by respiratory or digestive tract into the body and accumulation in the body, the lead content in the blood is 0.6 ~ 0.8 mg/L can damage the internal organs, and arsenic compounds will cause poisoning, so their levels should be as small as possible, and copper in the standard stipulated in the must not exceed 1.0 mg/L, while copper is not harmful elements, but it is not the more the better material, for pure water, one of the symbols of is to measure the degree of purity.

The organic index is mainly embodied in the national standard for the chloroform and carbon tetrachloride content of the provisions. Because the quality problem of barreled pure water providers in karachi is mainly concentrated on microorganism detection exceeding the standard, in order to solve this problem, many manufacturers are not from the production process, quality management, but only through the quantity to try to solve the problem of microorganism pollution of pure water, commonly used disinfectant for chlorine disinfectant such as chlorine dioxide. Barreled pure water can produce some new organic halogenates due to chlorination disinfection, the main components are trichloromethane (chloroform) and carbon tetrachloride and a small amount of monochloromethane, monobromodichloromethane, dibromodichloromethane and bromoform, etc., collectively known as halogenated alkyl. After detection, the halogenated alkanes content in the chlorinated drinking water and tap water is generally higher than that in the source water. Among them, chloroform and carbon tetrachloride are of high content, which is harmful to human body. If drinking chloroform and carbon tetrachloride for a long time, the purified water exceeding the standard will lead to liver poisoning or even canceration. In order to protect the health of consumers, the national standard gb17324-1998 clearly stipulates that the content of trichloromethane and carbon tetrachloride in drinking pure water shall not exceed 0.02mg/L and 0.001mg/L respectively.

In the national standards, the microbial indexes include the total number of colonies, coliform bacteria, pathogenic bacteria, molds and yeasts. From the detection of purified water in recent years, microbial indicators are one of the indicators that are easy to exceed the standard. This is due to microbial contamination in the production, processing, transportation and marketing of purified water. In production and processing, workers do not pay attention to personal hygiene, recycling bottles cleaning, disinfection is not strict, and even some manufacturers in order to reduce costs, recycling caps used again, due to the deformation of recycling caps, caused by the bottle mouth is not sealed may cause microbial pollution. The excess of microorganisms reflects the degree of water pollution. Among them escherichia coli achieves certain index, can cause human body diarrhoea. Pathogens include salmonella, shigella, staphylococcus aureus and streptococcus b. Salmonella, shigella contaminated water can cause acute intestinal infections, diarrhea, fever and other symptoms; The enterotoxin produced by staphylococcus aureus can cause poisoning, acute gastrointestinal symptoms and even life threatening. Streptococcus b is the main pathogen causing suppurative inflammation in human body. Mold and yeast widely distributed in nature, in the process of the growth of mold in the breeding in food absorb nutrients to the food in the food nutrition value is reduced, and odor, influence the sense of food, especially mould to grow in the process of producing toxins can cause chronic poisoning, severe cases can lead to cancer.

The content of nitrite is another important indicator in the national standard health index. Nitrite mainly comes from the nitrate in the soil near the water source, and the nitrate content is higher in the saline-alkali land, the nitrate fertilizer applied in large quantities and the soil short of molybdenum. Nitrite shall not exceed 0.002mg/L in the national standard.

In the production process of high purity water, anions and cations in water can be removed by electrodialysis, reverse osmosis and ion exchange resin technology. In general, the particles in water can be removed by ultrafiltration, membrane filtration and other technologies. Bacteria in water, at present, the domestic use of medicine or ultraviolet lamp irradiation or ozone sterilization method to remove; Water TOC is generally activated carbon, reverse osmosis treatment. In the field of high pure water application, the purity of water is directly related to the performance, reliability and threshold voltage of devices, leading to low breakdown, defects, and affecting the few children life of materials. Therefore, high pure water requires high purity and precision.

Natural dissolved gases in water mainly include O2, CO2, SO2 and a small amount of CH4, radon and chlorine. In the production process of high purity water, it is also necessary to remove such gases. In order to effectively remove impurities, some chemical fungicides, such as formaldehyde, hydrogen peroxide and sodium hypochlorite, were added in the process of producing high purity water. These are some of the reasons why high purity water is not drinkable.

So what is pure water? Pure water refers to the water quality pure, does not contain any harmful substances and bacteria, such as organic pollutants, inorganic salt, any additives and various impurities, effectively avoid the invasion of the human body all kinds of germs, its advantage is that can be safely effectively supplement moisture to the body, strong solubility, strong affinity to the human body cells, therefore, it can promote metabolism.

It is water produced after deep treatment by ion exchange, reverse osmosis, fine filtration and other appropriate physical processing methods. Under normal circumstances, in the production process of pure water, only 50% to 75% of the source water is used, that is to say, 1 kg of tap water or groundwater can only produce about 0.4 kg of pure water, and the remaining 0.6 kg of water cannot be used as drinking water, can only be used for other purposes.