An Annex 1 and Pharma 4.0 perspective on water quality

An essential part of the manufacturing of drug products is the use of water of different degrees of purity. The US Food and Drug Administration (FDA) defines eight different types of water: non-potable, potable (drinkable), purified, water for injection (WFI), sterile water for injection, sterile water for inhalation, bacteriostatic water for injection and sterile water for irrigation.¹ The last four are produced at separate plants and thus less discussed for pharma since they are unlikely to be producing them in house. In particular, purified water and WFI are critical when producing sterile pharmaceutical drug products. The difference is that purified water can be used for non-parenteral drugs, while WFI must be used for parenteral drugs. This naturally sets different requirements for the two types of water. WFI has the highest purity standards, which according to European Pharmacopoeia (Ph. Eur.) are, for example, less than 0.5ppm total organic carbon (TOC) and less than 10 colony forming units (CFU)/100ml.²