Guide for offices
Wiping vs destroying a hard drive: which does your company need?
In short
- NIST SP 800-88 Rev. 2 (September 2025) describes three levels of data sanitisation: clear, purge and destroy.
- Purge makes recovery infeasible even in a lab while keeping the drive reusable. Destroy does the same but leaves the drive unusable.
- Repeated overwriting is an old approach. NIST notes the US Defense Department dropped its overwriting specification in 2006, and says multi-pass overwriting gives very little protection on some drives, such as SSDs.
- Whatever method is used, ask for a certificate of sanitisation for each drive.
When old laptops and servers leave your office, the drives inside them are the real risk. "We formatted them" is not an answer an auditor or a client will accept. The good news is that there is a clear, widely used standard for this, and it boils down to one question: does the drive need to be usable afterwards?
The three levels, in plain words
NIST Special Publication 800-88, Guidelines for Media Sanitization, is the reference most IT teams and auditors use. Its latest revision, Rev. 2, was published in September 2025. It defines three methods:
| Level | What NIST says it does | Drive reusable? |
|---|---|---|
| LevelClear | What NIST says it doesUses software to sanitise all the storage a normal user can reach, protecting against "simple, non-invasive data recovery techniques". | Drive reusable?Yes |
| LevelPurge | What NIST says it doesUses physical or logical techniques to make recovery "infeasible using state-of-the-art laboratory techniques". | Drive reusable?Yes |
| LevelDestroy | What NIST says it doesMakes recovery infeasible with laboratory techniques and leaves the media unable to store data again. | Drive reusable?No |
In practice, clear is usually an overwrite with wiping software. Purge typically uses the drive's own built-in sanitise or secure-erase commands, or cryptographic erase on encrypted drives. Destroy means shredding, crushing, disintegrating or similar.
Why "DoD 3-pass" is out of date
You may still see wiping sold as "DoD 5220.22-M" or "7-pass DoD wipe". NIST Rev. 2 notes that hard drives were often erased this way in the past, but that the US Department of Defense removed its overwriting specification in 2006. It also warns that on some drives — for example SSDs with hidden spare capacity — multiple overwrite passes "should be avoided as very little confidentiality protection is achieved", and that purge or destroy should be used when more assurance is needed.
Which one does your company need?
| Situation | Sensible choice |
|---|---|
| SituationLaptop being reassigned to another employee inside the company | Sensible choiceClear is often enough for low-sensitivity data; purge if it held anything confidential |
| SituationLaptop or server leaving the company for refurbishment or resale | Sensible choicePurge, so the device can be reused but the data cannot be recovered |
| SituationDrive that is failing, will not respond to erase commands, or cannot be verified | Sensible choiceDestroy |
| SituationDrives that held highly sensitive data (finance, health, customer records, source code) | Sensible choicePurge with verification, or destroy, according to your own policy |
NIST leaves the final choice to each organisation's policy, based on how sensitive the data is. If you do not have a written policy yet, the table above is a reasonable starting point to agree with your IT and compliance leads.
Check that it worked
NIST says sanitisation results "should be inspected to verify that the sanitization technique was completed successfully". For wiping, that usually means a verification report from the software. For destruction, it can be a witness, photographs or video of the drives being destroyed, with serial numbers recorded.
Ask for a certificate for each drive
NIST recommends that "a certificate of sanitization … should be completed for each ISM [information storage media] that has been sanitized". A useful certificate records at least:
- Device and drive make, model and serial number
- The method and level used (clear, purge or destroy) and the tool or equipment
- Whether the result was verified, and how
- Date, location, and the name of the person who carried it out
Match these certificates against your own list of devices. Our guide on disposing of office laptops and servers covers the rest of the process.
Common questions
Is a quick format or "reset this PC" enough?
A quick format only removes the index to the files, so most data can be recovered with free tools. A full reset on a modern, encrypted laptop is better, but you still need a record showing what was done. For devices leaving your company, use a purge-level method or destruction and get a certificate.
Is physical destruction always safer than wiping?
Both purge and destroy aim to make recovery infeasible with laboratory techniques. Destruction is the right choice for failed drives or the most sensitive data, but it rules out reuse. Purge lets a working device be refurbished, which is better for the environment.
Does NIST still recommend multiple overwrite passes?
No. NIST SP 800-88 Rev. 2 describes multi-pass overwriting as a past practice, notes the US DoD removed its overwriting specification in 2006, and warns it gives very little protection on some drives such as SSDs.
What about phones and tablets?
Use the official erase option: Apple's Erase All Content and Settings, or Android's factory reset, which Google says erases all your data from the phone. Remove accounts and device locks first so the device can be reused, and record which devices were reset. Our home e-waste guide has the steps.
Related on this site
Sources
We checked the facts in this guide against these official documents. Rules change, so check the current version before relying on it for compliance.