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Overwrite free space in Windows 7/8 securely

It is a common misconception that if you delete files from your recycling bin, it is lost forever. In fact, depending on how long ago the file was deleted, it is possible to recover them. The reason for this is that although the files are deleted and you can no longer freely access them (in your recycle bin or elsewhere), they have actually only been marked ‘free to be overwritten’. As a result, these particular files contents are still located somewhere on your OS and will eventually be overwritten by new data. This is fantastic for computer users who may have accidentally erased an important file and need to reacquire it, although not for people who want to ensure that no one is able to ever restore this data. If you fall in the latter case, then this how to guide is for you. If you want to make certain that the files you just deleted have no chance of recovery, you can perform an operation that overwrites the files with random garbled data.


Navigate to Start and type CMD in the search box.


Right click CMD and select Run as Administrator from the drop down menu. When the User Account Control dialog box appears, click Yes to continue.


In Command Prompt, enter in the following: cipher /w :[drive letter]. In our example, we have entered in drive letter ‘E’.

Note: The drive letter refers to the drive you want to securely overwrite free data on. 

The data will be overwritten with three passes:

  • First with all zero’s – 0×00
  • Second with all 255’s, – 0xFF
  • Finally with random numbers


That’s it!

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