What Actually Happens During a Workplace Drug & Alcohol Test

It's more procedural — and more fair — than most people assume.

Workplace drug and alcohol testing is one of those things everyone has an opinion on, but very few people understand how it actually works. Having spent years running site testing, here's the process stripped of the myths.

"Non-negative," not "positive"

Under the relevant workplace safety frameworks, an on-site cup or saliva sample that shows a reading is never called "positive" — it's called non-negative. That's because on-site tests aren't lab-verified. A non-negative result triggers a second sample, and if that repeats, a third — with full chain-of-custody documentation. From that point, the sample is treated almost like evidence: signed over, tracked through every hand that touches it, right through to the lab.

Targeted vs. blanket testing

Employers generally have two options. They can test a specific individual if there's reasonable suspicion — but that opens the door to a workplace bullying complaint if it's perceived as targeting. Or they can run a randomised, algorithm-selected test across the whole site, which tends to be the fairer and more defensible approach, even though it's more expensive to administer.

It's not about punishment

The point of testing isn't to catch people out — it's risk management. If a result comes back non-negative, the standard approach in NSW is that the employer has an obligation to offer rehabilitation support, not simply discipline. Genuine substance issues get a pathway forward, including scheduled follow-up testing over months, which tends to work better as an incentive to stay clean than a one-off consequence ever could.

Why it matters more in high-risk roles

The stakes scale with the job. Someone operating a crane or heavy machinery under the influence isn't just a personal liability — they're a risk to everyone around them. And if a workplace was aware of a known issue and did nothing, that's a liability question for the employer too, not just the individual. Testing exists to protect the whole site, not to catch any one person out.