How to Securely Prepare Your Old Computer for Disposal

Before You Give Away or Discard Your Old Computer

How to Securely Prepare Your Old Computer for Disposal

For security reasons, you should never just give away or dispose of your old computer without properly wiping away your existing data. Simply deleting your old files or reformatting your hard disk is not enough, since the data can still be recovered from your computer by someone using a data recovery program. This article discusses the various steps that you will need to take before you donate your old computer to someone else or discard it.

Why You Should Never Simply Give Away or Throw Away Your Old Computer

For those who are not convinced that they need to properly wipe their old computers before disposing it, here are some reasons:

  1. Data Security: Deleting Your Files is Not Enough

    Do you think that deleting your old files, and clearing the Recycle Bin, is enough to remove them from your computer? Think again. When a file is deleted, it is not actually removed from the hard disk. All that is done is that a certain marker is set on the hard disk to indicate that the file is no longer available. The contents of the file are still present on the hard disk. If someone were to use a data recovery program, he/she may be still able to recover your file or portions of your file. The same is true of formatting a hard disk. Modern hard disk formatting utilities do not wipe the hard disk - they just reset some information in the hard disk. The data is still there.

    Incidentally, even if you know for sure that you never store vital information like credit card numbers in a document on your computer, you should still perform the procedure here.

    • Your credit card number may have been saved by a browser in a cached file at one time or another on your computer when you performed an online transaction. Caching is done automatically behind your back by modern browsers to speed up the browsing experience. Even if you have cleared your cache, the number may still be lurking on the hard disk somewhere.

    • It's not just credit card numbers that you need to protect. A lot of things are intricately connected with your identity. Your social security number, your name, the email addresses in your email software, etc. If you have ever written an office report on your computer, your name will surely be in that report somewhere, and fragments of that data may still be on the hard disk, though not visible to you. Many of these bits of information can be abused by others who want to steal your identity or sell your data or some other horrific thing that you probably can't imagine (but they can).

    • It's worse if you use Windows Vista, since Vista squirrels away copies of all the files you have saved unless you have turned off Volume Shadow Copy.

      Since it's impossible for you to recall every single thing you have ever done on your computer in the years that you owned it, always assume that some sort of critical information exist and that you need to securely erase them.

  2. Programs Registration Keys Security

    Data files are not the only files you need to clear. If you have purchased any programs on the Internet, you would probably have been given a licence key or registration number to enter into your program to activate it. These programs typically keep a copy of that key somewhere on your hard disk so that they can remember that you are a registered user. If you leave your registered programs and their keys on your system, someone might be able to retrieve it and distribute it on the Internet. When a key becomes widely available, the software author may blacklist it. As a result, when you try to install the software you paid for on your new computer, you may find that you can no longer register it, even though you have paid for it.

    This goes beyond software that you install. It applies to the very operating system (like Windows) as well. If you are running a retail version of Windows, that you separately bought from a software store, you may want to use it in your new computer. Since you are only licensed to use Windows on only one computer at a time, if you simply leave your old computer with your retail Windows installed, you may find one day that your existing Windows computer no longer works. This may happens if Microsoft discovers your key circulating on the Internet and blacklists it so that it is no longer valid.

I know the above sounds a bit paranoid, especially if you are not very computer proficient. However, from the point of view of any experienced computer user, recovery of electronic data and use/abuse of such data is very easy. We're no longer in the 20th century here, where it may take a criminal mastermind to perpetrate such crimes. Nowadays, even kids can do it.

Steps to Preparing for Disposal and Securely Wiping Your Computer

Disclaimer: the procedure described here is meant for an ordinary home user whose data doesn't really interest anyone other than small-time crooks. If your hard disk has really valuable data, whether commercial or governmental, please consult your organisation's security policies for proper disposal of your hard disks and computer. Also, this guide does not deal with solid state disks (SSD) which seems to be coming into vogue. I have no idea how to securely dispose those.

  1. Save Your Data

    Make sure that you have really made a copy of all your data in the computer first. Note that this doesn't only mean that you copy all the files in your "My Documents" folder or your Desktop or wherever you placed those files. It also means that you save all licence keys or registration keys from the programs that you have bought and installed on your computer.

    Get a USB drive or a flash drive and copy everything to it before you go onto the next step. Once you take the next few steps, your data is irrevocably lost to you.

  2. Download a Disk Wiping Software

    You need a special piece of software to do the secure wiping of your hard disk for you. Don't worry, you don't have to spend a cent. It's free.

    Go to's Free Secure File / Disk Erasing Utilities page and click through the link for Darik's Boot and Nuke (called "DBAN" for short) in the main section of that page. Once you are at the DBAN site, download the file for "floppy disks and USB flash drive" if your old computer has a floppy drive. If it doesn't, get the file for "CD and DVD media" instead.

    Note that the machine you're disposing must either have a working CD drive or a floppy drive.

  3. Create the Dban Disk

    If you downloaded the floppy disk version, place a blank floppy disk into your floppy drive, run the program you downloaded, and follow the instructions.

    If you downloaded the CD/DVD version, things are a bit more complicated. You need to have a CD burner to make a bootable DBAN CD. If your old computer does not have a CD/DVD burner, you will have to download and make the CD on your new computer (which I assume has a CD/DVD burner). To create the bootable CD, start your CD/DVD burning program and look for an option that allows you to burn a disk image.

    If you don't have a CD/DVD burning (ie, writing) program, get one from the Free CD and DVD Burners and Copying Software page and find out how to use it to write an ISO file.

    Note that it doesn't matter whether you use a CD-R or a CD-RW blank media, although you should probably use a CD-RW so that you can reuse the CD when you are finished with it. DBAN is not the sort of software that you will need to run every day.

  4. Reboot with Dban

    Once you've finished creating the DBAN CD or floppy disk, place it into the old computer's drive and restart the computer. You will be greeted with a blue screen with the heading "Darik's Boot and Nuke", and a list of options. Press the ENTER key to start DBAN in interactive mode.

    After a few seconds or so, you will see a new screen. In the main portion of the screen, under the title "Disks and Partitions", you will find a list with the manufacturer's name of your hard disks followed by the partitions present on that hard disk. Press the space bar until every single square bracket box "[]" either contains "[wipe]" or "[****]". In doing this, you're selecting every single hard disk on your computer for erasure.

    The default method of erasure is to overwrite your existing data on your hard disk 3 times. There are other options to erase your disk multiple times with different sorts of data. These options are supposed to make your data less likely to be recoverable, but will take a longer time. I leave you to discover how to activate those options yourself if you wish. (Hint: type "M" to see the various wipe methods.)

    The default option of wiping the disk only a few times will hopefully be enough to defeat casual snoopers looking through your hard disk for easy pickings. But you should note that such software wipes of your hard disks are not foolproof. There are ways of recovering data even after using a wipe, but they require expensive procedures (at the time I write this) that the average crook is not likely to use. On the other hand, if your hard disk contains things like truly secret information, that rivals are willing to pay to recover, the only safe way to ensure that the data is gone is to physically destroy the entire hard disk, platters and all. As mentioned earlier, the method I describe is meant for the ordinary person's home computer that only contains things that interest small-time crooks.

    To start the wipe, hit the F10 key at the top of your keyboard. Note: once you do this, your data is doomed. Do not press the key unless you are really sure. If you decide not to press F10 after all, the only way to quit Dban is to turn off the computer.

    The entire erasing procedure will take a long time, so you should not sit in front of your screen waiting for it to finish. Depending on the size and speed of your hard disks, the number of hard disks you have, the method of erasure you selected, it can take many hours, or even more. It may be best to connect the computer to an unused power socket in the corner of a room, and leave it overnight to work on its own.

    Once Dban is finished (it will tell you), just remove your floppy disk or CD and turn off the computer. You cannot reboot the computer after that, since, with the hard disk wiped, there is no operating system like Windows to boot to any more.

  5. If You Are Giving Your Computer Away...

    If you are donating your computer to someone, you may not want to give them a computer that cannot even boot, which at this moment is the state your computer. They might think it is spoilt and just throw it away. You will need to install some sort of operating system onto the computer.

    If your computer is a branded computer that came with its own system restore CD, you can simply boot to that CD and use the system restore facility to restore the computer to the default factory setup that you got when you first bought the computer. The system restore CD is useless on any other computer anyway, so it's not like you can use it on your new system.

    For those that don't have a system restore CD or who have lost it, you can always download a free operating system and install it into the computer. Linux is especially good for this purpose. It comes not only with a fancy easy-to-use interface like Windows but also has lots of preinstalled programs like an office suite, multimedia programs, web browser, etc. And they are all free, and installed out of the box with the operating system. You can choose whichever flavour of Linux you wish, but if you can't decide and have the time to download a DVD-sized file, I suggest trying the OpenSUSE distribution (which is listed on the free Linux systems page). It's a complete system, is simple to install, and comes with most of the things that a computer user needs.

    Linux is usually distributed in ISO files (like Dban), so you'll need to burn it to a DVD or CD, boot into it in your old computer, and install it. After installing, you may want to play around with it to make sure everything works. Remember to write down any usernames and passwords you create when you install it so that you can give it to the person you're donating to.

What If Your Computer Cannot Even Boot?

The above procedure is well and good if your computer still works. If your computer is in such a bad shape that it can't even boot, then you'll probably not be able to even wipe it. In such a case, you may want to remove its hard disk and physically destroy it before you dispose of the computer. I leave to your imagination how you can destroy a hard disk, although I should mention that simply scratching the circut board on the surface of the hard disk is not enough to destroy the data.


Once you've done the above, your system should be good to go. You removed any potential valuable data from the eyes of casual snoopers, and, if you have taken the trouble to reinstall an operating system as suggested above, you have left the system in a usable state that the person you have given it to can still use.

Copyright © 2008-2013 by Christopher Heng. All rights reserved. Get more "How To" guides and tutorials from

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