A method of sterilization of a load comprising the step of determining whether said load is wet comprising the steps of: a. evacuating a chamber to a first pressure, said first pressure being both sub-atmospheric and above the vapor pressure of water at the temperature of the load; b. isolating the chamber at the first pressure for a first predetermined time period comprising a first transient period and a first correlation period following the first transient period; c. during the first predetermined time period periodically recording pressure data including a pressure measurement of the pressure in the chamber and the time the pressure measurement is taken; d. calculating a first rate of pressure rise during the first correlation period using the pressure data periodically recorded during the first predetermined time period; e. further evacuating the chamber to a second pressure, said second pressure being below the vapor pressure of water at the temperature of the load; f. isolating the chamber at the second pressure for a second predetermined time period comprising a second transient period and a second correlation period following the second transient period; g. during the second predetermined time period periodically recording pressure data including a pressure measurement of the pressure in the chamber and the time the pressure measurement is taken; h. calculating a second rate of pressure rise during the second correlation period using the pressure data periodically recorded during the second predetermined time period; and i. comparing the second rate of pressure rise to the first rate of pressure rise, and identifying the load as not too wet for sterilization to proceed if the second rate of pressure rise is below the first rate of pressure rise. a. evacuating a chamber to a first pressure, said first pressure being both sub-atmospheric and above the vapor pressure of water at the temperature of the load; b. isolating the chamber at the first pressure for a first predetermined time period comprising a first transient period and a first correlation period following the first transient period; c. during the first predetermined time period periodically recording pressure data including a pressure measurement of the pressure in the chamber and the time the pressure measurement is taken; d. calculating a first rate of pressure rise during the first correlation period using the pressure data periodically recorded during the first predetermined time period; e. further evacuating the chamber to a second pressure, said second pressure being below the vapor pressure of water at the temperature of the load; f. isolating the chamber at the second pressure for a second predetermined time period comprising a second transient period and a second correlation period following the second transient period; g. during the second predetermined time period periodically recording pressure data including a pressure measurement of the pressure in the chamber and the time the pressure measurement is taken; h. calculating a second rate of pressure rise during the second correlation period using the pressure data periodically recorded during the second predetermined time period; and i. comparing the second rate of pressure rise to the first rate of pressure rise, and identifying the load as not too wet for sterilization to proceed if the second rate of pressure rise is below the first rate of pressure rise.