Why the method matters
Not all data destruction is equal. The method you choose determines whether a device can be reused, whether destruction can be independently verified, and whether your process meets recognised standards such as NIST Special Publication 800-88 or NCSC secure sanitisation guidance. Selecting the wrong method can leave data fully recoverable — or result in a compliance gap under UK GDPR and the Data Protection Act 2018.
For context on the legal obligations, see our overview of what is secure data destruction.
Comparison: data wiping vs shredding vs degaussing
| Data wiping | Physical shredding | Degaussing | |
|---|---|---|---|
| How it works | Software overwrites every storage sector with random or patterned data | Mechanical shredder reduces the device to fragments | Powerful electromagnet demagnetises the storage medium |
| Works on HDDs | Yes | Yes | Yes |
| Works on SSDs | Yes (with certified software) | Yes | No — ineffective |
| Works on tapes | Yes (some formats) | Yes | Yes |
| Works on USB/flash | Yes (with certified software) | Yes | No — ineffective |
| Device reusable after? | Yes | No | No (HDD rendered inoperable) |
| Verifiable? | Yes — software produces a verification report | Yes — chain of custody + witnessed destruction | Partial — no sector-level verification |
| Certificate issued? | Yes | Yes | Yes |
| Relevant standard | NIST SP 800-88, NCSC guidance | NCSC guidance, HMG IA Policy No.5 particle size requirements | NCSC guidance (magnetic media only) |
| WEEE compliant disposal? | Device may be reused or recycled | Fragments recycled via authorised treatment facility | Device must be recycled |
Data wiping explained
Data wiping — also called overwriting or data erasure — uses software to write new data over every addressable location on a storage device. Because the original data is overwritten at the sector level, it cannot be recovered with standard forensic tools.
The effectiveness of wiping depends on the software used and how it handles edge cases such as remapped sectors and wear-levelled flash memory. Certified wiping tools produce a verification report that confirms every sector was successfully overwritten. This report is the primary evidence of compliance and forms part of the certificate of data destruction.
NIST SP 800-88 (Guidelines for Media Sanitisation) sets out accepted overwrite approaches and distinguishes between “clear” (suitable for lower-sensitivity data) and “purge” (required for higher-sensitivity data). The NCSC publishes similar guidance aligned to UK government classification levels.
Wiping is the preferred method when devices will be reused or donated, because it preserves the hardware. At Recycle4Charity, wiped devices that pass our quality check are donated free of charge to digitally-excluded Londoners.
Physical shredding explained
Physical shredding uses a mechanical shredder to reduce storage media to small fragments, making data recovery physically impossible. Industrial shredders used for IT asset destruction are rated by the particle size they produce — smaller fragments represent higher security assurance.
HMG IA Policy No.5, which governs the destruction of UK government-classified information, specifies maximum particle sizes for different classification levels. For TOP SECRET magnetic media, for example, the particles must be below a defined size threshold (refer to current NCSC secure sanitisation guidance on ncsc.gov.uk for the latest particle-size specifications).
Shredding is the most certain method of destruction for all device types, including SSDs and USB drives, because it destroys the physical medium regardless of how data was stored. It is the method of choice when a device has no residual value, when the data is of the highest sensitivity, or when the device type cannot be reliably wiped (for example, certain enterprise SSDs with non-standard firmware).
The fragments produced by shredding are recycled as raw materials through authorised treatment facilities, in compliance with the WEEE Regulations 2013.
For more on shredding specifically, see our detailed guide to hard drive shredding explained.
Degaussing explained
Degaussing exposes a storage device to a powerful magnetic field that randomises the magnetic domains on which data is recorded. For traditional hard drives and magnetic tapes, this renders the data permanently unreadable.
However, degaussing has a critical limitation: it is entirely ineffective on solid-state storage. SSDs, USB flash drives, SD cards, and smartphones store data using NAND flash memory, which is not magnetic. A degaussed SSD is functionally unchanged — the data remains fully intact. This is a common and dangerous misconception.
Degaussed hard drives are also rendered permanently inoperable — the servo tracks that allow the drive heads to navigate the platters are destroyed along with the data — so the device cannot be reused. The degaussed drive must then be disposed of through a WEEE-compliant recycling route.
Because degaussing does not produce a sector-level verification report, some auditors regard it as less verifiable than software wiping. It is often used as a precursor to physical shredding to add an additional layer of assurance.
Which method should you choose?
The right choice depends on three factors: device type, data sensitivity, and whether the device will be reused.
- Reusing the device? Use certified software wiping. It is the only method that allows a device to be returned to service.
- SSD, USB drive, or flash memory? Do not use degaussing. Use software wiping or physical shredding.
- Magnetic hard drive or tape, highest sensitivity, no reuse? Degaussing followed by shredding provides the highest assurance.
- Mixed estate of devices, large volume? A certified ITAD provider can apply the appropriate method to each device type and provide a single certificate covering the entire batch.
For organisations with specific compliance requirements — government contracts, regulated industries, or particularly sensitive data categories — review the current NCSC secure sanitisation guidance and, where applicable, HMG IA Policy No.5 before selecting a method.
Recycle4Charity offers certified data wiping and physical shredding for London businesses. Every collection includes a certificate of data destruction. Visit our data destruction for business page to find out more, or contact us to arrange a collection.