This is what the company states btw
Hospira Sterile Water for Injection is a sterile, non-pyrogenic, distilled water in a single-dose vial used for intravenous administration after addition of a suitable solute. It may also be used as a dispensing container for diluent use. No antimicrobial or other substance has been added. The pH is 5.5 (5.0 to 7.0). The osmolarity is 0.
This preparation is designed solely for parenteral use only after addition to drugs that require dilution or must be dissolved in an aqueous vehicle prior to injection.
Sterile Water for Injection contains no bacteriostat, antimicrobial agent or added buffer and is supplied only in single dose containers to dilute or dissolve drugs for injection. For IV injection, add sufficient amount to a solute to make an approximately isotonic solution. pH 5.0 to 7.0.
Water for Injection, is chemically designated H2O.