The only way to permanently destroy data, without physically destroying the hard disk, is by multiple overwriting of the data by generating and recording random characters across the entire surface of the drive, resulting in all data being destroyed and file sizes reset to zero. There are an increasing number of overwriting standards which people refer to including the American Military standard DOD 5220.22-M or Infosec Enhanced Standard 5. Basically these standards dictate that the drive has to be over written
a minimum 3 times. Weee IT uses the latest CESG approved overwriting software that exceeds this standard and allows us to overwrite our customer's hard drives up to a maximum of ninety-nine times. In the event that a hard disc cannot be data erased or if it is below 60GB the drive will be shredded. All company references including permanent security markings will be removed from equipment, prior to resale. In the event that permanent security markings cannot be removed, equipment will be forwarded for disposal.