Deleting your data from computers, laptops and other devices

Getting rid of your computer? Laptops, mobile phones and other devices may contain personal information that you wouldn’t want others to see, such as passwords and credit card information.

It’s important to properly delete any personal information before you sell or dispose of your hardware, so that it cannot be accessed by anybody else either by mistake or for malicious purposes.

Also, if you have a device that is faulty think about what personal data is stored on it before you dispose it. Remember that just because a device will not turn on does not necessarily mean that the data is not accessible by someone.

Personal data can be stored on any device with a permanent memory, including desktop and laptop computers, external hard drives, games consoles, mobile phones, tablets, faxes, printers, and removable memory such as that found in digital cameras. When deciding what to do, consider the type of media the data is stored on and whether or not this is easily accessible.

Options for secure deletion

Pros

Cons

Physical destruction

This involves physically destroying the media so that it can no longer be used.

Once destroyed, data on the media will not be recoverable except using specialist, expensive equipment.

You can destroy the media without specialist equipment.

If you can remove the media you can destroy it separately and leave the device intact.

This is a good method of destruction for removable media such as CDs and DVDs.

You will have to replace the destroyed media with a new storage facility if you want to use the device again.

If you are not able to remove the media from the device you will have to destroy the device itself.

Removing the media may invalidate the warranty.

Fragment particles raise health, safety and environmental complaints. Consider specialist help for devices with hazardous elements eg mobile phones and batteries.

Secure deletion software

This involves using software to overwrite data one or more times.

Simple and cheap.

The media can be reused once the overwriting is complete.

Large drives may take some time to overwrite multiple times.

Ineffective on some media such as write-once CDs.

It may be difficult or impossible to remove the media from the device.

Restore to factory settings

Many devices offer a function to ‘Restore to factory settings’. This will return the device to the state in which you bought it.

Can be used on devices which do not have removable or otherwise accessible storage media.

This method relies on the device manufacturer to have implemented a secure wiping stage into the factory reset process.

You should check with the device manufacturer to determine if this is sufficiently secure.

Send to a specialist

There are many organisations which will securely delete data from a range of devices and types of media. These organisations will destroy or overwrite your data on your behalf.

A specialist organisation may be able to return, reuse or recycle your media or device after they have securely deleted your data.

You will need to check the organisation’s processes to be sure that your data will be securely deleted.

If you can, you should perform another secure deletion method or at least a ‘restore to factory settings’ before you send a device to a specialist organisation.

Formatting

Formatting media recreates the data structures and file system.

A full format can be used in conjunction with overwriting to provide further assurance that data cannot be recovered.

A reformat is not sufficient to securely delete data because the data can be easily recovered using freely available software.

Where will I find my data?

Desktop and laptop computers will have a hard drive inside where your data is stored. Above you'll see some common types of hard drives found in PCs and laptops.

Don’t forget that you may have personal data stored on other memory types such as USB drives, CDs and DVDs and SD cards (eg in a camera or mobile phone).

My data is in the cloud. How do I delete this securely?

Securely deleting data from the cloud or other remote storage service cannot be achieved by you running overwriting software. You should contact your cloud provider to see what service they offer to securely delete the data.

Where do I get overwriting software from?

Software products which can perform the secure deletion of data are available from IT security firms. There are also other software products (often free) which you can download and use. However, when obtaining software from the internet you should make sure this comes from a reputable source and that you review evidence that the software has been tested against the claims that it makes.

I cannot decide between physical destruction and overwriting.

In choosing between physical destruction and overwriting, the main point to consider will be whether or not you want to use the media again. Physical destruction will completely destroy the media so it is only appropriate if you are sure that you do not want to use it again.

What is the difference between data deletion and data destruction?

Data deletion is when data is removed and is no longer available in plain sight and can’t easily be recovered. If you perform a ‘quick format’ of your hard drive or perform a factory reset of your device, you will be typically deleting data. It’s not enough to send an item to your recycle bin to delete it, you need to remove it from there too. Data recovery experts can restore this data but even with that said, data deletion is generally an adequate method of removing personal data from a device in most situations.

In contrast, data destruction is when data is removed from your device and can never be restored, even by professional data recovery experts. Examples of data destruction are physical destruction of the data storage, secure data removal software or sending the data to a specialist data destruction company. You might consider data destruction if you feel the data on the device is of such importance that you would not want to risk the data ever being recovered by someone else.

Can I get someone else to securely delete data from my equipment?

Yes. If you are not confident in performing the deletion yourself you can get assistance from a professional who has experience in this area.