How To Erase Data So No One can Recover it

When you delete a file, it isn't really erased, it continues existing on your hard drive even after you empty the recycle bin. This allows you and other people to recover files you've deleted. If you are not careful, this will also allow other people to recover your confidential files even if you think you've deleted them.

What Happens when you delete a File?

If you're wondering why your computer doesn't just erase files when you delete them, it's actually pretty simple. Deleting a file's pointer and marking its space as available is an extremely fast operation.

In contrast, actually erasing a file by overwriting its data takes significantly longer. For example, if you a deleting a 10 GB file, that would be near-instantaneous. To actually erase the file's contents, it may take several minutes just as long as you were writing 10 GB of data to your hard drive.

Preventing Deleted Files From Being Recovered

You can use a utility that automatically wipes your hard drive's free space - by writing other data over the free space on your hard drive, all deleted files will be erased.

For example, CCleaner's integrated Drive wiper tool can do this.

To make sure that a single file can't be recovered, you can use File Shredding application such as Eraser to delete it. When a file is shredded or erased, not only is it deleted but its data is overwritten entirely, preventing other people freon recovering it.

To really prevent someone from recovering any of your data, you can use a disk wiping program such as DBAN (Darik's Boot and Nuke). Burn DBAN to a CD, boot from it and it will erase everything from your hard drive including your operating system and all your personal files, overwriting them with useless data. This is very useful when getting rid of a computer - it helps you ensure all your personal data is erased.