When it’s time to donate or recycle an old electronic device, there’s one top priority to have: complete data destruction. It’s never been more important, with 16.6 million people experiencing identity theft in the U.S. in 2012. That’s a total of $24.7 billion in financial losses domestically, according to the U.S. Bureau of Justice Statistics

Normally, people associate personal data theft with high profile data breaches like the Home Depot and Target credit card breaches in late 2013, or credit card skimmers. But identity theft hits improperly wiped business computers as well. Britain’s National Health Service in Surrey was fined £200,000 when confidential information of 3,000 patients turned up on one of its recycled computers. The computer was being auctioned on eBay. 

It just goes to show that you never know where computers go or who gets a hold of them once they are recycled. Sensitive data could literally turn up anywhere, leaving you at risk. Fortunately, hard drive data destruction offers a secure solution. Below is your comprehensive guide to data destruction.

Types of data destruction

To start, data destruction comes in three common types:

Overwriting:

This common and easy method just involves overwriting old data with new data. This method can be completed with software. It can be done on a whole machine or part of one. However, it can take a long time to wipe a large drive, security is down while this process runs and it cannot wipe certain protected areas. It also doesn’t work on damaged computers that are not in a state to be rewritten. Plus, errors could leave certain data not overwritten. So if you’re in a situation where you need a lot of very secure data wiped, overwriting is probably not your best bet.

Degaussing:

In this process, the magnetic field of a storage disk or drive is removed. You’d do this with a degausser device. It’s applied to hard disks, floppy disks or magnetic tape. Once the process is complete, the data is totally unrecoverable, so it’s a nice permanent solution. On the other hand, the devices are expensive and have proven to be risky to the safety of nearby electrical equipment, since they emit a magnetic field. They can also permanently damage hard drives during the data destruction process. In short, this method is really only a good idea if you’re preparing a machine to be scrapped and/or are a professional.

Physical destruction:

If you really want to be on the safe side, the most complete way to destroy data is to have an e-waste recycler or data destruction company shred, melt or generally annihilate the storage components. It’s the most secure option, but can also be the most expensive. This is another option for if you are completely planning on replacing your hardware, of course. It’s also not very eco-friendly, since the recycling/reuse options are greatly reduced. 

For the most secure and total way to nuke your data, these are the three basic options you have. It might be tempting to just delete a file and assume it’s gone forever, but it’s still on your computer. All deleting a file does is remove the file entry from a specific folder, so disk space is labeled as free and available at that specific location. Data is still there, waiting to be overwritten at some point, maybe. With that in mind, there are several other best practices to follow when deleting data.

Data destruction best practices

The Privacy Technical Assistance Center through the U.S. Department of Education outlined some good practices to have in regards to destroying data. They’re meant specifically for school systems, of course, but a few of the points are universally applicable: 
  • If you are ever working with a third party, draft agreements that provide requirements stating any secure information provided will be totally destroyed once the data is no longer needed. Stipulate how the data is to be destroyed. Make sure responsible parties sign certification forms. 
  • Again, don’t rely on the easy way of getting rid of data. The U.S. Department of Education lists file deletion, disk formatting and one-way encryption as insecure ways of deleting data. All of these leave the data in the machine and open for retrieval with the right tools. Make sure to go with some of the more permanent solutions listed above. 
  • Create official processes within an organization for deleting data. 
Yet most of these tips and methods, so far, have included ways to destroy highly confidential and large amounts of data. What if you just want to clean up a personal hard drive that doesn’t have any world-shattering information on it?

Data destruction tips and tricks for at home

PCWorld has a good resource for securing your data yourself. If you’re going specifically for a hard drive erase, you’ll want to go with block-overwrite software. The article states, “Block-overwrite software is more versatile… because it lets you wipe data from a hard drive while leaving the operating system, program files and other keepers intact. Unfortunately, this type of software is ineffective on SSDs or USB flash drives, and in many cases it can’t wipe a hard drive’s HPA (Host Protected Area), which contains data about the low-level organization of the drive. That said, with high-powered algorithms and multiple passes, it will effectively render your data unreadable even when subjected to all but the most expensive forensic techniques.” 

Some examples of this type of program are O&O SafeErase 7 (sitting at a $30 price tag), MediaTools Wipe 1.2 (with a $99 price tag) and Active@ KillDisk Pro (costing $40-50). Active@ KillPro also has a free option that will overwrite free space or partitions with a bunch of zeroes. 

There’s also a free option called Eraser 6, which is a utility that deletes files, folders and free space at set intervals. It’s what you’d get if you’re the sort who doesn’t go back and access files, and you want to maintain a clean, minimal presence on your computer. For a complete hard drive wipe, you can find a tutorial for using a free program called Derik’s Boot and Nuke here

Otherwise, if you’re about to donate or sell your personal computer, you can find a list of secure computer disposal tips for PCs here and Macs here. Microsoft recommends going to a certified refurbisher if you plan to donate your machine.