You don’t need to be a genius to know that driving while intoxicated is a bad idea. In fact, a modicum of intelligence is all it takes to know that getting behind the wheel after drinking is one of the most irresponsible things anyone can do.

But what’s interesting is how comparatively few people know if and when it is safe to get back behind the wheel after consuming alcohol. Or for that matter, how much they can get away with drinking, without being considered to be over the limit.

Sadly, drink driving accidents and incidents have a habit of going up in the summer, as people spend more of their time out and about.

Most drivers are cautious when it comes to alcohol and driving, but evidence suggests that issues with drink driving are still rife. Each year, somewhere in the region of 8,000 deaths or injuries appear on UK roads, entirely due to one or more motorists being over the legal limit.

Of course, this doesn’t even scratch the surface when it comes to near misses, or those who get away with drink driving without being caught.

As with most things, knowledge is power. The more you know about drink driving, the easier it becomes to stay on the straight and narrow.

UK Drink Driving Limits

In terms of official limits on alcohol, there are slightly different rules in Scotland and in the rest of the UK.

In Wales, England and Northern Ireland the drink-drive limit is:

  • Micrograms per 100 millilitres of breath – 35
  • Milligrams per 100 millilitres of blood – 80
  • Milligrams per 100 millilitres of urine – 107

In Scotland these limits are slightly lower:

  • Micrograms per 100 millilitres of breath – 22
  • Milligrams per 100 millilitres of blood – 50
  • Milligrams per 100 millilitres of urine – 67

All well and good, but these numbers don’t really mean a great deal to most people.  After all, the human body’s ability to break down and expel alcohol differs significantly from one person to the next. 

Hence, there is no way of knowing exactly what level of alcohol is in your system, based on how many drinks you have consumed, or when you consume them.

How Fast Does the Body Break Down Alcohol?

It’s often said that for each unit of alcohol consumed, it takes 1 hour for the alcohol to be removed from your body. Hence, for a pint of beer or a large glass of wine, you’re looking at a ‘processing’ time of two hours. 

But this doesn’t take into account the hour or so it takes for alcohol to be fully absorbed into the body. Hence, drinking four pints of beer and getting behind the wheel eight hours later might not be nearly sufficient.

In any case, head out for a night on the tiles and chances are there’s no way you’ll be in a fit state (in a legal sense) to drive the next day. If you were to consume seven fairly strong drinks throughout the course of the evening, you’d be looking at a minimum alcohol processing time of 21 hours.

Given how a lot of people drink considerably more than this on a big night out, you’re more or less out of order from driving for the next full day and night.

More to follow in the second half of our drink driving guide, coming soon…