How do I get rid of a computer but keep my private data private?

This is a simple question that I’m often asked by my computer support clients. Pity the answer isn’t as simple. In fact, it can be complicated – technically and/or financially.

If the drive is in situ in a complete computer and you wish to dispose of it as a working machine then you have to clean the private stuff off it by deleting it and then ensuring that the deleted data can not then be undeleted. I will be covering the principles of this in next week’s blog.

If the drive is already out of the machine and/or if the main intention is safe and secure disposal of the computer (without expecting the computer to continue to function) then it may be simplest just to keep the drive (as this is the only part of the computer that stores any of your private information) and dispose of the the rest of the machine without worrying about data security.

This strategy also has the advantage that the retained drive can be viewed as a backup of your data at the time you disposed of the machine. In theory, you should be able to read any data on the drive, even though you no longer have the computer it came from. In practice, I have found that hard drives that are not used for a length of time can fail to “spin up” when you try to read them – see this blog on Long Term Data Retention.

2.5 inch drive enclosure

2.5 inch drive enclosure – you can’t tell from the outside whether it is SATA or IDE (or both)

To try to read a drive that has been separated from its computer, you just need an external drive enclosure from somewhere like PC World, Maplin, or Amazon. This is a box into which the drive fits and which includes the electronics to allow the drive (in its new box) to be externally connected to another computer via a USB cable. In fact, all old drives can be fitted into enclosures this way and used, for instance, as backup drives. If possible, take the drive with you when going to buy such an enclosure as there are two questions that have to be answered correctly if you are to get the right enclosure:

  • Is this a 2.5 inch drive or a 3.5 inch drive? (in practice, laptop drives are 2.5 inch and desktop drives 3.5 inch)
  • Is it a SATA drive or an IDE drive? (if the computer is newer than about four years it’s likely to be SATA)

3 1/2 inch drive enclosure

3.5 inch drive enclosure – note that 3.5 inch enclosures have their own power supply

In practice, keeping old drives to use as backup drives in this way is not as useful as it used to be as the enclosures cost about £15 and the drive (since it is likely to be 2-5 years old) is probably quite small by today’s standards and might also be getting to the age at which the chances of it failing are starting to increase rapidly. If your main priority is getting a backup drive then it would probably be better to start from scratch and buy a new external drive for £45-£80. See this blog on External Backup Drives.

The conclusion from all this is that it’s worth retaining a drive from an old computer as this is a simple and secure method of (non)disposal. You also know that there’s a chance of reading it at a future date if you need to get some data off it.

The problem for a “normal” user is “how do you get the drive out of the computer”?

3.5 inch SATA drive

3.5 inch SATA drive

If it’s a desktop computer then there will be screws on the case of the main system unit that retain one or both of the side covers. After removing the cover(s), just look for a metal rectangular box similar to that captioned here as “3.5 inch SATA drive”. The precise method of removal varies between models of computer and varies between being “simple” to remove and “well nigh impossible: how on earth did they put this thing together?” The good news, of course, is that you’re probably not bothered about breaking anything as you are probably not passing this computer on to anyone as a potentially working machine.

2.5 inch IDE drive

2.5 inch IDE drive

If it’s a laptop computer then you are hoping to find one, two, or four screws on the bottom of the laptop that either retain a plate (the removal of which will reveal the hard drive), or which retain the drive itself (the removal of which allows the drive to be slid out from either the left or right edge of the laptop).

2.5 inch SATA drive

2.5 inch SATA drive – it is the connectors at the edge that differentiate it from an IDE drive

If you are unlucky, there are either no such screws or you can’t identify them. In that case, you will need to remove pretty well all of the many screws on the underside of the laptop in the hope that you can get the case apart and then remove the drive (which will be a 2.5 inch drive as shown). I strongly advise against pulling a laptop computer apart if you are hoping to keep the machine alive for another owner.

Next week I will look at the options for keeping your data safe when disposing of a computer with the drive left in situ.

Hard disc with cover removed

Hard disc with cover removed - don't ever remove the cover if you want the drive to work again!

Disposing of your old computer may not be as easy as might imagine.

You can not simply put it in a wheelie bin, destined for landfill. Computers contain several metals that will poison the ground. There are EU laws banning disposal in this way. Either take it to a local authority waste disposal site or contact your council to make a special collection.

Before disposing of it, though, it is prudent to ensure that no-one can get at the data on it. This applies whether the machine is going to cyber heaven or on to a new owner. Here’s a list of the broad options available to you:

If the computer is condemned

1) Remove the hard drive and keep it.


    1) If the the drive is still readable then this gives you a backup of your data. You will need some means – such as an external USB drive case – to connect this drive to your new computer if you wish to read it.

    2) There is no possibility of its contents falling into the wrong hands.


    1) It can be a bit of a chore geting the drive out of the case (particularly on older laptops).

    2) You do have to keep the drive somewhere (although, as my mother used to say, “it won’t eat any meat”)

2) Remove the hard drive and destroy it.

If you open up the case of a hard drive and deface the mirror-like surfaces with a screwdriver or sandpaper then you are almost certainly putting it beyond any readability or use. I agree that it may be technically possible for someone with all the right (very expensive and specialist) equipment to read fragements of the drive, but I would rather start worrying about the possibility of being hit by a meteor than worry about this happening.


    1) There is virtually no possibility of data falling into the wrong hands

    2) You don’t have to keep the drive


    1) You haven’t retained any backup of your old machine

    2) It can be a bit of a chore actually geting the drive out of the case (particularly on older laptops).

    3) It can be difficult to open up the case of a hard drive in order to deface it

3) Delete everything off the hard drive

You could use a software utility such as CCleaner to completely wipe the drive (including the operating system and all programs and data – whether deleted or not)


    1) Easier than removing the drive

    2) You can’t forget to delete specific data files


    1) You need to install and run the software and it can then take quite a long time to “scrub” the drive in this way (particularly if you set the software to make multiple “passes” over the drive).

If the computer is going to a new home

Removing the drive is a bit drastic. It is likely that the new owner won’t have the expertise to source a new drive, install it, and re-install the operating system and software. In fact, even if s/he does have the knowledge and resources it is very likely that it just won’t be worth doing. So, the aim is to pass on the computer so that it can be used with the minimum of fuss but without compromising your data. The options are:

1) Delete sensitive information

This includes your data files, your browser history, saved passwords etc. You may also need to un-install software that is licensed to you that you intend to install on your new machine.


    1) This is the least amount of work you need to do in order to protect your data.


    1) You may miss some data when deleting.

    2) The deleted data may be recoverable. If you have the slightest doubt about the integrity of the new owner or the destiny of the drive then the data that you think you have deleted could be vulnerable. This is because “deleting” data in the normal way does no such thing. What actually happens is that the operating system maintains a directory of the files that occupy the different parts of the drive. When you delete a file it simply changes the directory such that the space occupied by the (deleted) file is now eligible for re-use (ie the space can be over-written with a new file). The file itself is still present on the disc until the space is re-used and it can be “un-deleted” using special software tools.

Scrubbing brush and hard disc

2) Delete sensitive information and then “scrub” the drive

This consists of deleting the data as above, but then running special software that over-writes the space that may still be occupied by readable data. The software that I recommend for this is Piriform’s CCleaner.

Even this process can sometimes be “reversed” by highly specialised people and facilities. Frankly, I’m back to worrying about the meteor before worrying about this possibility. And if you are as paranoid as this, then you may also wish to consider the possibility of data still being present on the drive due to the drive head having shifted fractionally over time such that data you wrote onto the disc a long long time ago is still readable at the very edge of the tracks of data.


    1) Fairly easy to do and should satisfy the non-paranoid


    1) You may still fail to delete important data

    2) Won’t satisfy the paranoid. If you belong in this category,then I recommend that you read this article on data remanence

3) Delete everything off the hard drive

You could use a software utility such as CCleaner to completely wipe and scrub the drive (including the operating system and all programs and data).


    1) You can be sure that you didn’t leave anything behind that you would rather have deleted.


    1) You need to install and run the software and it can then take quite a long time to “scrub” the drive in this way (particularly if you set the software to make multiple “passes” over the drive).

    2) The new owner will need to re-install the operating system and software.

Conclusion: whether your old computer is at the end of its life or going to a new home you will almost certainly need to take steps to protect your confidential data prior to disposal.

© 2011-2019 David Leonard
Computer Support in London
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