Water of extremely high purity. In the integrated circuit industry, it is used for the cleaning of semiconductor raw materials and utensils, the preparation of lithography masks and the water vapor source for silicon wafer oxidation. In addition, other solid-state electronic devices, thick-film and thin-film circuits, printed circuits, vacuum tubes, etc. also use ultrapure water. Ultra-pure water: water that not only removes the conductive medium in water almost completely, but also removes undissociated colloidal substances, gases and organic substances in water to a very low degree. The resistivity is greater than 18MΩ*cm, or close to the limit value of 18.3MΩ*cm (25℃). Ultra-pure water is difficult to achieve by general process. The resistivity can reach 18.25MΩ*cm(25℃) by adopting four major steps of pretreatment, reverse osmosis technology, ultra-purification treatment and post-treatment and various treatment methods such as multi-stage filtration, high-performance ion exchange unit, ultra-filtration filter, ultraviolet lamp and TOC removal device. Ultra-pure water is produced by distillation, deionization, reverse osmosis or other appropriate supercritical fine technologies in order to develop ultra-pure materials (semiconductor original materials, nano-fine ceramic materials, etc.) in American scientific and technological circles. Apart from water molecules (H20), there are almost no impurities in this water, and there are no bacteria, viruses, chlorine-containing dioxins and other organic matters. Of course, there are no mineral trace elements needed by human body. Generally, it is not directly drinkable, which is harmful to human body and will suck out human body.