ultrapurewater

Ultrapure water (UPW) is water of exceptionally high chemical purity used in applications where trace contaminants can affect processes or measurements. UPW is defined by very high resistivity and extremely low levels of dissolved ions, organic carbon, particulates, and microorganisms. In many industries, a common target is a resistivity of at least 18.2 megohm-centimeters at 25°C, with total organic carbon and inorganic impurities kept to the lowest practical levels.

Production of UPW typically involves a multi-stage purification train. Pretreatment may include filtration and deionization or softening to remove hardness and particulates. Primary purification often relies on reverse osmosis or distillation, followed by fine polishing through ion exchange, mixed-bed deionization or electrodeionization, and final steps such as ultraviolet oxidation or microfiltration. The aim is to minimize ionic content, organic carbon, endotoxins, particulates, and microbial presence. Continuous recirculation with online sensors for resistivity or conductivity and for TOC helps maintain purity, and systems are designed to minimize recontamination from air, piping, or storage vessels.

Applications of UPW are concentrated in semiconductor fabrication, pharmaceutical and biotech manufacturing, and analytical laboratories. In semiconductor manufacturing, UPW is used for rinsing and cleaning to prevent residue formation. In pharmaceuticals and labs, it serves as a reagent and solvent for analytical techniques, formulation, and sample preparation. UPW is not intended for human consumption and handling emphasizes clean, compatible materials and controlled storage to prevent recontamination.

Quality control often follows industry standards and internal specifications, including measurements of resistivity/conductivity, TOC, microbial content, and particulate counts. Standards such as ASTM D1193 describe water types and purity criteria that guide UPW production and testing.