Completely wiping a computer’s hard drive is an important step when getting rid of an old device or to protect sensitive data. There are a few ways to securely erase data from a hard drive, but some are more effective than others. This guide will walk through the different methods and explain how to securely wipe your computer.
Why Do I Need to Securely Wipe a Computer?
There are a few key reasons why you should wipe a computer before disposing of it or passing it on to someone else:
- Remove personal and sensitive data – Things like financial information, passwords, browsing history, documents and photos.
- Avoid identity theft – Wiping the drive prevents someone else from accessing your private data.
- Remove malicious software – Formatting the drive helps get rid of any malware, viruses or other infections.
- Prep for recycling or donation – Wiping lets you securely donate or recycle old computers.
Simply deleting files or reformatting the hard drive does not fully remove data. The files are only marked as deleted rather than being permanently erased. Data recovery software could potentially recover them.
How Does Deleting and Formatting Differ From Securely Wiping a Drive?
When you delete files or reformat a hard drive, it simply marks the existing data as deleted rather than actually erasing it. The files are removed from the file table, allowing new data to overwrite it. Until that happens, data recovery software can scan the drive and potentially recover the “deleted” files.
Securely wiping a drive goes beyond simple file deletion. It completely overwrites the entire hard drive with random data to make previous files unrecoverable. The two main methods are:
- Overwrite with zeros – This replaces all data with zeros in a single pass.
- Multi-pass random overwrite – Data is overwritten repeatedly with random characters.
Overwriting with zeros is quicker, but data remnants may still exist. Using multiple passes with random data ensures all previous files are fully unrecoverable. Secure erase programs use verifiable data erasure algorithms approved by government agencies and militaries.
What Are the Different Ways I Can Wipe a Hard Drive?
There are a few options to securely erase data from a hard drive:
Use Built-In Tools
Some operating systems have secure erase features built-in:
- Windows – Diskpart Erase command and Disk Wipe utility
- Mac – Disk Utility Secure Erase option
- Linux – shred command
These perform a quick overwrite with zeros to wipe the drive. However, they may not be as secure as third-party utilities.
Use Third-Party Erasing Tools
More secure options are to use software programs specifically designed for wiping drives:
- Darik’s Boot and Nuke (DBAN) – Free to download and boot from a USB or CD
- Active@ KillDisk – Offered as a bootable tool or installable application
- Eraser – Free open source secure deletion for Windows
- Disk Wipe – Free Mac erase tool for single or multi-pass overwrites
These give you features like multiple overwrite passes, verification, wiping free space and erasing full disks or partitions.
Physically Destroy the Drive
For maximal security, you can physically destroy the hard drive. This may be recommended if the drive contains highly sensitive data.
Methods include:
- Using a hammer to damage the platters and circuitry
- Drilling holes through the PCB and platters
- Running a strong magnet over the drive to corrupt data
- Taking the drive apart and sanding the platters to remove the magnetic coating
Physically destroying the drive is time consuming and permanent. But it provides the highest level of assured data removal.
How Do I Securely Wipe a Hard Drive in Windows?
Windows has a couple options for securely erasing a hard drive:
Using Diskpart Erase Command
Diskpart is a command line tool for managing disks and volumes. To use it:
- Open the Command Prompt as administrator
- Type
diskpartand press Enter - Type
list diskto identify the disk number for the drive you want to wipe. Look for the size to verify it’s the correct disk. - Type
select disk X(replace X with the disk number) - Type
cleanto perform a quick wipe, overwriting the drive with zeros - Type
exitto close Diskpart
This performs a basic single pass wipe to overwrite existing data with zeros.
Using Disk Wipe Utility
Disk Wipe is a free utility provided by Microsoft that can perform more secure drive erasure. To use it:
- Download and install the Disk Wipe utility
- Open Disk Wipe
- Select the drive you want to securely wipe
- Choose a single pass or up to 35 multi-pass options
- Click Wipe Disk button to start the process
Disk Wipe provides verification after wiping to ensure the drive has been securely erased with random data.
How to Securely Wipe a Mac Hard Drive
On Macs, you can use the built-in Disk Utility app to securely erase a hard drive.
- Open Disk Utility
- Select the disk or partition you want to wipe from the left sidebar
- Click the Erase button
- Choose a format type – APFS or Mac OS Extended
- Select the Scheme: GUID Partition Map
- Under Erase, choose a security option:
- Fastest – Single pass overwrite
- Most Secure – Multi-pass overwrite
- Click Erase to wipe the drive
The Most Secure option performs a 35-pass erase process, overwriting data repeatedly with random data. This ensures complete secure deletion.
How to Wipe a Hard Drive Using Darik’s Boot and Nuke
Darik’s Boot and Nuke (DBAN) is a free self-contained boot utility designed to securely wipe drives. To use it:
- Download DBAN and create bootable media on a CD/DVD, USB or floppy disk
- Configure the BIOS to boot from the DBAN media
- Boot from the media to open the DBAN interface
- Select the drive to wipe with the spacebar and press Enter
- Choose a wipe method – Quick Erase, DOD Short or DOD 5220.22-M
- Press F10 to start the wiping process
- Allow the process to fully complete without interruption
DBAN provides both a quick erase and military-grade multi-pass random wipes fully compliant with DoD erasure standards.
Can I Recover Data After Wiping a Hard Drive?
With most secure wipe methods, it is virtually impossible to recover data from a drive after it has been fully erased. However:
- With a quick single pass zero wipe, remnants of some files may still exist.
- Solid state drives (SSDs) can potentially retain data in spare areas.
- Specialized forensic recovery using scanning electron microscopes have had limited success in lab conditions recovering overwritten data.
But for the average user, fully overwritten hard drive data cannot be recovered by any normal means.
How Long Does It Take to Wipe a Hard Drive?
| Method | Time |
|---|---|
| Quick Erase | 30 minutes to 2 hours |
| 1 Pass Overwrite | 2+ hours |
| 3 Pass Overwrite | 5+ hours |
| 7 Pass Overwrite | 12+ hours |
Erase times depend on the drive capacity and speed of computer. Quick erases can take under an hour while multi-pass overwrites will take many hours. Be prepared to leave the computer wiping overnight.
Conclusion
Securely wiping a hard drive is the only way to completely erase sensitive files before disposing of, recycling or repurposing a computer. While simple file deletion leaves data recoverable, tools like DBAN and Disk Wipe overwrite all data to prevent recovery.
The best options are to use multi-pass random data overwrites or to physically destroy the hard drive. With proper secure erasure, you can ensure no usable data remains on the drive.