Purified water is an essential resource in all laboratory environments. Water is often the major component in such diverse applications as buffer preparation and organ perfusion.

Purified water is a common requirement within hospital and healthcare laboratories, in particular, infection control and pathology laboratories, where water is used both for cleaning and disinfection, and as the basis for making up cell cultures, buffers and reagents.  In each case, the systems used for generating purified water have to function reliably and efficiently, producing water to rigorous standards and qualities of up to 18.2MΩ.cm, yet be simple to setup and use.

Typically, a water purification system will be built around a reverse osmosis (RO) unit.  This takes potable water, normally from a mains supply, and feeds it under pressure into a module containing a semi-permeable membrane.  The membrane removes a high proportion of impurities, including up to 98% of inorganic ions, together with virtually all colloids, micro-organisms, endotoxins and macromolecules;
RO systems generally include a pre-treatment package designed to meet the characteristics of the feed-water, especially in areas with hard water or high levels of organic contamination. Typically, this equipment includes a base-exchange softener to remove hardness that would otherwise create scale in downstream membranes, plus activated Carbon filters to remove free Chlorine and organic contaminants, with any remaining particulates being removed by a fine filter before the pre-treated water enters the RO unit.

RO systems are extremely sophisticated and efficient, in isolation they are capable of producing water to a quality specified as Grade 3 (up to 1.0MΩ.cm) or Grade 2 (up to 10.0MΩ.cm) for applications such as glassware cleaning, or Grade 1 (up to 18.2MΩ.cm), for applications such as ion chromatography and clinical analyzer feed.
These include a deionization stage, introduced after the RO membrane, additionally; processes such as UV disinfection and sub-micron (typically 0.2 microns) filtration can also be used.