Systems and methods for controlling humidity. Methods can include providing a chamber configured to receive objects to be sterilized injecting a first quantity of water into the chamber determining a pressure rise and a pressure drop in the chamber resulting from the first injection calculating an absorption ratio (AR) as the ratio of the pressure drop to the pressure rise sensing the humidity of the chamber after the first injection to determine a first humidity value (RHchamber) comparing the first humidity value to a pre-selected humidity value (RHsetpoint) to determine a humidity error (RHerror), wherein RHerror=RHsetpoint−RHchamber and injecting a second quantity of water into the chamber, wherein the second quantity of water is calculated based on the absorption ratio (AR) and the humidity error (RHerror). Systems can perform the method and the systems and methods can be employed in a sterilizer.
