NIST 800-88: Clear, Purge & Destroy explained
Three words sit behind nearly every serious erasure policy: Clear, Purge, and Destroy. Here's exactly what they mean.
NIST Special Publication 800-88 Revision 1, "Guidelines for Media Sanitization," is the reference most organisations cite when they define how to erase storage. It groups sanitization into three outcomes, each tied to how much effort an attacker would need to recover the data.
Clear
Clear protects against non-invasive recovery — the kind anyone with standard software could attempt. It makes data infeasible to recover using ordinary tools, but doesn't guarantee protection against laboratory equipment. Overwriting a drive, ATA Secure Erase, and NVMe Format all typically qualify as Clear.
Use Clear when a drive is staying inside your organisation — redeployed to another desk or repurposed internally.
Purge
Purge protects against laboratory recovery techniques. It renders data unrecoverable even with specialised equipment, using techniques that reach below the operating system's view of the drive. ATA Enhanced Secure Erase, NVMe Sanitize (cryptographic or block erase), and cryptographic erasure of self-encrypting drives all qualify as Purge.
Use Purge whenever a drive leaves your control — resold, returned to a lessor, recycled, or sent for repair.
Destroy
Destroy makes the media itself unusable, so data is unrecoverable because the device no longer functions. Shredding, disintegration, incineration, and degaussing are all destruction techniques.
Destroy is the fallback when erasure isn't possible — a failed drive, a frozen drive, or one locked behind Block SID lockdown.
The outcomes side by side
| Outcome | Protects against | Typical techniques | Use when |
|---|---|---|---|
| Clear | Non-invasive recovery | Overwrite, Secure Erase, NVMe Format | Redeploying internally |
| Purge | Laboratory recovery | Enhanced Secure Erase, Sanitize, crypto erase | Drive leaves your control |
| Destroy | Any recovery | Shredding, disintegration, degaussing | Erasure not possible |
How tScrub maps to NIST 800-88
tScrub classifies every drive and runs the strongest method the hardware supports, then records the resulting outcome — Clear, Purge, or a Destroy flag — in the report. The full method-to-outcome mapping is on the compliance page.
FAQ
Is NIST 800-88 a legal requirement?
It's a guideline, not a law — but it's the language regulators and auditors use, so aligning to it makes compliance conversations much simpler. See GDPR, HIPAA, and ISO 27001 for the actual obligations.
Which outcome do I need?
Purge for anything leaving your control; Clear for internal redeployment; Destroy only when erasure fails.