There is a loose guide that a persons breath/alcohol level will reduce by 7-8 micrograms per hour. Roughly suggesting that you could return from the legal limit of 35mg to zero in four to five hours. That would be if you had drunk up to the limit and then stopped.
If you had drunk a skinful then it may take longer to recover the last bit from 35 to zero as your bodies ability to recover may be reduced from dealing with the excess alcohol.
The difficulty for Joe Average is that unless you have an accurate measurement to start with, or the facility to continue testing with, you will never know from what breath/alcohol concentration you are starting from. Your 'seat of the pants' best guess could be way of, with unthinkable consequences!
The vast majority of the consumed alcohol is dealt with by the liver. It can only process at its own rate, and cannot be rushed.
Exercising, drinking water, eating can have a very minor effect in making the body excrete alcohol, but it is still negligible in the over all drink drive limit scheme of things. Most of the benefit comes from these things simply making you feel better, without reducing alcohol levels.
Body size and composition also does not have a huge effect on the livers ability to deal with booze. The big variable is how much one can drink relative to the breath or blood alcohol level. If you have big lungs and lots of blood you will need to consume more alcohol to reach the same concentration as a smaller person. The rate that you feel that you get pissed can be affected by your size, gender, body composition, diet, activity, drinking habits, type of drink, the weather, the relative positions of celestial bodies, sexual orientation, your lottery numbers . . . . . . . . . it can be completely variable for the same person on different occasions.
Coming back to the OP's question and my earlier point, there is no point in doing this by guess work as the variables are infinite. If you need to know categorically that you are under the limit at any given time then the only way to do it is with a calibrated breath test device. Handheld devices are variable in their accuracy (even home office approved types). The only definitive answer would be found in custody blocks all across the land. But that could have a bit of a knock on effect to your subsequent ability to drive!!!
Now I like a slurp as much as the next borderline alcoholic, but the simple answer is to moderate or abstain on school nights
, I have no problem about not driving after drinking, but it is the morning after that worries me, particularly as I drive a van and could be classed as a proffesional driver. I went to Halfords to see what they had for breathalysers, but were sold out.
, and I like to think I have good absorbsion? but guesswork won't work with the law.
