Technical records: what to keep and for how long (clause 7.5)
Records must let the measurement be repeated under conditions as close as possible to the original, and every amendment must show who changed what, when.
Clause 7.5 requires technical records for each laboratory activity to contain the results, report and sufficient information to facilitate, if possible, identification of factors affecting the result and its uncertainty, and to enable repetition under conditions as close as possible to the original.
Design principle
Keep inputs and outputs together with their provenance: which reference, which values, which software version, which person, which time. Amendments must be tracked — the original data and the amended data both retained, with the identity of the person making the change and the date.
What this means for software
- Calculation inputs and outputs stored, not just the final number.
- Version of the calculation code recorded with each result.
- Review and approval actions recorded with user, timestamp and outcome.
- Audit trails that cannot be silently edited.
The test the clause sets
Clause 7.5.1 does not give a list of documents to keep. It gives a standard to meet: the records must contain enough information to identify factors affecting the result and its uncertainty, and to enable the activity to be repeated under conditions as close as possible to the original. Every filing decision follows from that sentence. If a competent stranger could not reproduce the measurement from what is on file, the record is incomplete however many forms are in it.
| Question a stranger would ask | Record that answers it |
|---|---|
| What was measured, at what points? | Item identity and serial, measurand, set points as actually achieved |
| With what? | Reference standard identity and its certificate, readout and version, bath or block identity |
| Under what conditions? | Ambient temperature and humidity, immersion depth, measurement current, stabilisation time |
| What were the raw numbers? | All readings, not the mean alone — the spread is evidence about repeatability |
| How was the answer computed? | The uncertainty budget with its sources, divisors and coefficients; the software version |
| Who did it and when? | Operator, date, times of individual readings |
| Who checked it? | Reviewer, date, and what the review covered |
Immersion depth and ambient temperature are the two most often missing, and they are the two that most strongly determine whether a repeat gives the same answer.
Amendments, and the original that must survive
Clause 7.5.2 requires that amendments be traceable to the previous version or to the original observations, that both the original and the amended data be retained, and that the person making the alteration be identifiable. On paper that is the single line through, initialled and dated, with the reason. In software it is an audit trail that records the previous value, the new value, the person and the timestamp — and that cannot be switched off or edited.
Overwriting is the failure mode, and it is usually accidental: a spreadsheet cell corrected in place leaves no evidence that anything was ever different. That is the practical reason spreadsheet-based technical records are hard to defend.
Retention
- The standard sets no universal period; the laboratory defines one and justifies it. Common practice is the calibration interval plus a margin, or a fixed term such as six years, whichever is longer.
- Contractual and regulatory obligations may be longer than your own policy, and where a customer works to GMP the retention that binds them will reach you.
- Records must remain readable for the whole period. A proprietary logger format with no export path is a retention failure waiting to happen — archive the raw export alongside it.
- Archived records still need their access controls and audit trails; moving a record to cold storage does not lift clause 7.5.2.
Frequently asked questions
- How long must calibration records be kept?
- The standard sets no fixed period; accreditation bodies and regulated customers typically expect several years and at least one full calibration cycle beyond the instrument's life.
References
- [1]ISO/IEC 17025:2017 — General requirements for the competence of testing and calibration laboratories
General technical guidance written against the cited sources. It is not regulatory or legal advice and does not replace the applicable standard, guideline or a qualified reviewer's judgement.
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