Double RO that is, bipolar reverse osmosis it is the use of reverse osmosis technology to filter the second pure water. Thus further removing a large number of organic components in the water, heavy metal ions, harmful impurities and bacteria. After EDI equipment again, greatly reducing the impurities in the water, thereby greatly reducing the conductivity, is free of impurities closer to the chemical meaning of water (H2O), commonly used in the electronics manufacturing industry, medical industry, biological engineering, injection manufacturing and a wide range of other fields