Water for Injection (WFI) meets specific standards of sterility and purity defined by the European Pharmacopoeia, as it is used for the preparation of drugs for parenteral administration, both as a vehicle and to dissolve or dilute substances or preparations. Proper monitoring of operation and maintenance of the system itself are essential.

WFI is produced, stored and distributed under conditions that prevent the growth of microorganisms and avoid any other contamination. In order to ensure adequate water quality, validated procedures must be in place, as well as in-process monitoring of electrical conductivity, TOC (total organic carbon) and microbial contamination. According to pharmacopeias, WFI can be produced by multiple effect distillation.