In addition to general purity standards, industry-specific distilled water standards further refine adaptation needs, among which the pharmacopoeial standards in the pharmaceutical industry are the most stringent. Pharmaceutical purified water (PW), following USP <645>, EP 2.2.36 and Chinese Pharmacopoeia standards, has a conductivity of ≤2.0 μS/cm, no microorganisms, no pyrogens, and is mainly used for the preparation of oral preparations, external preparations and cleaning of pharmaceutical utensils. Its advantage is that it meets pharmacopoeial compliance requirements and moderate cost, and the disadvantage is that it cannot be used for injection products; water for injection (WFI), as the highest standard in the pharmaceutical industry, follows USP <1231>, EP and Chinese Pharmacopoeia specifications, with a conductivity of ≤1.3 μS/cm, sterility, pyrogen-free, and extremely low TOC. It is the core raw material for the production of injections, infusions, and vaccines. Its advantage is extremely high safety, which can eliminate pyrogen reactions and ensure medication safety. The disadvantage is that the production cost is extremely high, and it needs to be stored and transported in cold chain throughout the process to prevent pollution.
Ultra-pure water (UPW) dedicated to the electronics/semiconductor industry, following ASTM D5127 and SEMI F47 standards, has a resistivity of 18.2 MΩ·cm, ion content below 1 ppt, no particles, sterility, and low TOC. It is specially used for core links such as wafer cleaning, photolithography, CMP, and chip manufacturing. Its advantage is that it can meet the needs of nanoscale manufacturing and eliminate circuit failures caused by trace impurities. The disadvantage is that the equipment cost is high, the maintenance is complex, and the purity requirements for the delivery pipeline are extremely high. Distilled water dedicated to industrial boilers/cooling, following GB/T 1576 and ASTM D807 standards, has a conductivity of ≤10 μS/cm, low hardness, low silicon, and no oil. It is used in high-pressure boilers, steam turbines, and industrial cooling systems, which can effectively prevent equipment scaling and corrosion and extend the service life of equipment. The disadvantage is that water quality indicators need to be monitored regularly, and the maintenance cost is higher than that of ordinary industrial water.
