Sterile water for injection is a sterile, nonpyrogenic preparation of water for injection that is used as a diluent or solvent for other parenteral drugs. It is a clear, colorless, odorless liquid that contains no bacteriostatic or antimicrobial agents. Sterile water for injection is used only after addition of drugs that require dilution or must be dissolved in an aqueous vehicle prior to injection. It is also used as a source of water for parenteral fluid replenishment after suitable additives are introduced. Before such use, other substances generally must be added to make the solution more or less isotonic. Sterile water for injection is available in single-dose containers and is chemically designated H2O. It is generally made by distillation or reverse osmosis and should contain less than a mg of elements other than water per 100 ml. Sterile water for injection is a pharmaceutic aid (vehicle) and parenteral fluid replenisher after addition of an appropriate solute. It is contraindicated for intravenous administration without additives because it is a hemolytic agent due to its hypotonicity.