Feed Water Parameters for Water for Injection:
For systems producing Drinking Water, there is no defined feed water requirement (chemical or microbial) for the system. However, the product water must meet the chemical and microbial attributes for EPA’s NPDWR (or comparable regulations of the European Union, Japan, or World Health Organization), be free of coliform bacteria, and have a total viable bacteria value of <500 cfu/mL. These product water parameters apply to feed water for a USP Purified Water or USP Water for Injection system. Obviously, since packaged waters refer back to the USP Purified Water or Water for Injection specifications, they are also produced from a system with feed water meeting the NPDWR.
Method of Production—Water for Injection
The method of production for Water for Injection may vary with pharmacopeias. An example is EP and USP Water for Injection production methods. The USP Water for Injection Official Monograph defines as:
Water for Injection is water produced by distillation or a purification process that is equivalent to or superior to distillation in the removal of chemicals and microorganisms.
The EP Water for Injection Monograph states that:
Water for Injection in bulk is obtained from water that complies with the regulations on water intended for human consumption laid down by the competent authority or from purified water by distillation in an apparatus of which the parts in contact with the water are of neutral glass, quartz, or suitable metal and which is fitted with an effective device to prevent entrainment of droplets. The correct maintenance of the apparatus is essential. The first portion of the distillate obtained when the apparatus begins to function is discarded and the distillate is collected.
Formulation of product for consumption in countries or regions complying with EP must employ distillation for production of Water for Injection.