HR & Workforce · Best Practice · Construction

Drug and Alcohol Test Record

A record of drug and alcohol tests carried out on site workers.

Last reviewed: 29 March 2026 — This guide reflects UK law as of this date. MHSWR 1999 / Contract remains current with no amendments enacted as of 29 March 2026. Next scheduled review: 29 March 2027.

Legal basis	Management of Health and Safety at Work Regulations 1999 (MHSWR) / Contractual requirement — no standalone UK statute mandates drug and alcohol testing, but employers have a duty under MHSWR to assess and manage risks including impairment
Test types	Pre-employment, random, for cause (reasonable suspicion), post-incident, and return to work
Test methods	Urine, oral fluid (saliva), breath alcohol, and hair analysis
Chain of custody	Critical for evidential integrity — every sample must be tracked from collection to laboratory result using a documented chain of custody procedure
Accreditation	UKAS-accredited testing providers are recommended to ensure laboratory results are legally defensible and meet ISO 17025 standards

1. Drug & Alcohol Testing

Safety-critical construction sites require a zero-tolerance approach to drug and alcohol impairment. Workers under the influence of drugs or alcohol present an immediate and serious risk to themselves, their colleagues, and the public. The Management of Health and Safety at Work Regulations 1999 require employers to carry out suitable and sufficient risk assessments, and impairment from drugs or alcohol is a foreseeable risk that must be managed. While there is no standalone UK statute that mandates workplace drug and alcohol testing, the employer's general duty of care under the Health and Safety at Work etc. Act 1974 and the specific requirements of MHSWR provide the legal framework for implementing a testing programme.

The drug and alcohol test record documents every test carried out on site, including the type of test, the method used, the chain of custody for the sample, and the result. The chain of custody is critical — if a test result is challenged (for example, at an employment tribunal or disciplinary hearing), the employer must be able to demonstrate that the sample was collected properly, sealed in a tamper-evident container, labelled with the worker's details, and transported securely to the laboratory without any break in the chain. Any gap in the chain of custody can render the result inadmissible.

Testing may be carried out at five key points: pre-employment (before the worker begins work on site), random (unannounced testing of a randomly selected sample of the workforce), for cause (where there is reasonable suspicion that a worker is impaired), post-incident (following a workplace accident or near miss), and return to work (before a worker who previously tested positive is permitted to return to duties). All testing should be conducted by trained collectors using validated testing kits, and confirmatory laboratory analysis should be carried out by a UKAS-accredited provider.

Use UKAS-accredited testing providers

Laboratory analysis of drug and alcohol samples should be carried out by a provider accredited by the United Kingdom Accreditation Service (UKAS) to ISO 17025. UKAS accreditation provides independent assurance that the laboratory operates to the highest standards of accuracy, reliability, and quality management. Results from non-accredited laboratories may be challenged and found to be unreliable in disciplinary proceedings or employment tribunal hearings. When selecting a testing provider, confirm their UKAS accreditation status, the substances included in their standard panel, their turnaround times for confirmatory results, and their ability to provide expert witness testimony if required.

2. Content

The drug and alcohol test record must capture the following information for every test carried out. Accurate and complete records are essential for evidential integrity and for defending any subsequent challenge to the test process or outcome.

Field	Detail
Test reference	A unique reference number assigned to each test for tracking and audit purposes, linked to the chain of custody documentation
Worker name	Full name of the worker being tested, verified against photographic identification at the point of sample collection
Date / time	The date and time at which the sample was collected — this is critical for correlating results with the worker's attendance and any incident under investigation
Location	The site or location where the sample was collected, including the specific testing room or area used to ensure privacy during collection
Test type	The category of test: pre-employment, random, for cause (reasonable suspicion), post-incident, or return to work
Test method	The method of sample collection: urine, oral fluid (saliva), breath alcohol, or hair analysis. The method used may depend on the substances being tested for and the testing provider's protocols
Collector	The name and qualifications of the person who collected the sample. Collectors should be trained in sample collection procedures and chain of custody requirements
Substances tested	The specific substances or substance groups included in the test panel (e.g. cannabis, cocaine, opiates, amphetamines, benzodiazepines, alcohol)
Chain of custody	Confirmation that the chain of custody procedure was followed: tamper-evident container used, sample labelled and sealed in the worker's presence, chain of custody form signed by the worker and collector, and secure transport to the laboratory
Immediate result	The result of any on-site screening test (negative, non-negative, or invalid). A non-negative screening result must be confirmed by laboratory analysis before any disciplinary action is taken
Laboratory result	The confirmed result from the UKAS-accredited laboratory: negative, positive (with substance and concentration), or insufficient sample. Only confirmed laboratory results should be used for disciplinary decisions
Action taken	The action taken following the test result: cleared to work, suspended pending laboratory confirmation, referred to occupational health, disciplinary process commenced, or removed from site
Worker signature	The worker's signature confirming their identity, consent to the test, and acknowledgement that the sample was collected and sealed in their presence

3. Common Mistakes

Not using chain of custody kits

The chain of custody is the single most important element of the testing process from an evidential perspective. If a sample is not collected into a tamper-evident container, sealed and labelled in the worker's presence, signed by both the worker and the collector on a chain of custody form, and transported securely to the laboratory, the result can be challenged and may be ruled inadmissible. Many site-level testing programmes use simple screening kits without any chain of custody documentation, which is adequate for an initial screening but entirely inadequate if the result needs to be relied upon in a disciplinary hearing or tribunal. Every non-negative screening result should trigger a confirmatory test using a full chain of custody kit, collected by a trained collector, and sent to a UKAS-accredited laboratory.

Not briefing workers on the drug and alcohol policy before testing

Workers must be made aware of the employer's drug and alcohol policy before any testing takes place. The policy should be communicated during site induction and should clearly state which substances are covered, the types of testing that may be carried out (pre-employment, random, for cause, post-incident, return to work), the consequences of a positive test, and the worker's rights including the right to request a B sample analysis. Testing workers who have not been briefed on the policy exposes the employer to claims that the testing was conducted without informed consent. The policy must also address prescription medication — workers taking prescribed medication that may cause a positive result should be required to declare this to the testing provider before the sample is collected, so that it can be taken into account during the laboratory analysis.

4. Frequently Asked Questions

Can an employer dismiss a worker who tests positive for drugs or alcohol?▾

Yes, but only if the correct procedure has been followed. The employer must have a clear drug and alcohol policy in place that the worker has been made aware of, the testing must have been carried out in accordance with that policy, the chain of custody must be intact, and the result must be confirmed by a UKAS-accredited laboratory (not just a site screening test). Even with a confirmed positive result, the employer must follow a fair disciplinary process in accordance with the ACAS Code of Practice on Disciplinary and Grievance Procedures. This includes informing the worker of the allegation, holding a disciplinary meeting at which the worker has the right to be accompanied, considering any mitigating circumstances (such as prescription medication, a request for rehabilitation support, or a first offence under a policy that provides for a second chance), and providing the right of appeal. Summary dismissal for a first positive test may be justified in safety-critical roles where the employer can demonstrate that the worker's impairment posed an immediate and serious risk to safety, but each case must be assessed on its own facts. Dismissing without following a fair process risks a successful unfair dismissal claim at an employment tribunal.

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