Will I get caught in alcohol testing?

It’s a question, as alcohol testing specialists, Integrity Sampling gets asked regularly and it’s a question you may have asked yourself, perhaps after enjoying a few drinks with friends at a bar or over dinner. So, just how long will alcohol stay in your system?

The issue with a question like this is that while the science can be relatively exact (see below) the result isn’t and can be difficult to determine until you actually take the alcohol test, which may well be too late. Let’s explore why in more detail.

Alcohol testing is simply a matter of adding up the numbers, isn’t it?

In part, the blood alcohol level (BAC) you would expect to produce during alcohol testing can be calculated.

For example, we know that it takes the average person around an hour to process one standard alcoholic drink. Furthermore, we know that a standard drink will increase the average person’s BAC to 0.015. So, therefore, the average person will be able to drink three standard drinks in an hour and just be under the legal limit in most states and territories of Australia, which is 0.05.

So, unless you failed maths, you’re probably still with us. That’s good, because it gets a bit more complicated from here!

The binge factor

The calculations above get a bit tricky once you get into the 2nd hour after you’ve consumed 3 standard drinks in the first hour. Don’t be fooled into thinking you can drink 3 standard drinks in the 2nd hour (and in the 3rd hour and so on) and still be under 0.05. There is a compounding factor in play, which means the average person will be over 0.05, and perhaps well over, if they drink another 3 standard drinks in the 2nd hour after they’ve already had 3 standard in the first hour.

The ‘standard’ factor

The other big issue you might have picked up is that we constantly state standard drinks in this article. That’s not necessarily one glass of beer or one glass of wine.

In the case of wine, for example, one standard drink is only 100mls. That’s less than ½ a cup of wine. In many pubs and restaurants the glass of wine you get may easily be 200mls. Drink two glasses in an hour and then drive… Well, you do the maths!

The individual factor

Even if you are extremely diligent in counting your drinks and knowing how many standard drinks you’ve consumed in a given time, there is another factor that virtually makes it impossible to know what you’ll blow during alcohol testing, until the result flashes up on the breathalyser. This is the individual factor.

The amount of alcohol you can process in a given time may be more or less than someone else, and more or less than the average person. It can even be different for you today than it would be tomorrow or the next day, even if you had exactly the same amount of alcohol in the same time.

These individual factors include age, sex, body size, body fat and general health. It can also include tiredness and how much you’ve had to eat, which is why it can vary from day to day.

Play it smart

If you don’t want to fail alcohol testing or, more importantly, have an accident because you shouldn’t be driving, the best solution is to play it smart and be over cautious. Perhaps you can have 3 standard drinks in an hour, but it’s probably best to make it only 2.

Dinner with wine may be more expensive than you think, if it causes you to fail roadside alcohol testing on the way home.


Michael is the founder of Integrity Sampling and is responsible for overseeing all national operations. He is based at Integrity Sampling's head office in Thomastown and is also responsible for the co-ordination of drug and alcohol testing within Victoria, assisting in the implementation of drug and alcohol (fit for work) policies and the presentation of drug and alcohol education and awareness programs. You can connect with Michael Wheeldon on LinkedIn

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