How long does alcohol stay in your system, and what is the legal limit in South Africa?
How long alcohol takes to leave the body, what blood, breath, urine and hair tests can see, and the South African drink-driving limit, with the exact wording of the law.
Alcohol stays in your system until the liver has cleared it, at about one South African standard drink every hour and a half, and nothing speeds that up. A local standard drink is 12 g of pure alcohol; an adult body gets through around 8 g of pure alcohol in an hour (NHS). Coffee, a cold shower or a litre of water leave that rate where it is. Behind the wheel the line is 0.05 g per 100 ml of blood, and the National Road Traffic Act treats reaching that exact figure as an offence.
Doing these sums every week? Message us on WhatsApp. A free, confidential call, and we reply the same day.
How long does alcohol stay in your system?
For most adults the liver clears about one South African standard drink every hour and a half, whatever you do. The average adult processes around 8 g of pure alcohol in an hour (NHS), and a South African standard drink holds 12 g.
Most of the alcohol is broken down in the liver by the enzyme alcohol dehydrogenase (ADH), which turns it into acetaldehyde, a toxic compound. The work runs at a steady rate, however much you drink. That is why a fourth glass does not make the first three leave faster.
Within an hour of one UK unit (8 g) there should be, in theory, little or no alcohol left in the blood of an adult, although this will vary from person to person (NHS). Treat every hour count on this page as that: a sum for an average adult, in theory. In our own house at Renewed Life Center, in Lakeside, Cape Town, nobody relies on the sum: everyone is breathalysed on arrival and at random during the stay.
| Standard drinks drunk (12 g each) | Pure alcohol | Hours for an average adult, in theory |
|---|---|---|
| 1 | 12 g | About 1.5 |
| 2 | 24 g | About 3 |
| 4 | 48 g | About 6 |
| 8 | 96 g | About 12 |
This is an estimate of when the body may have finished with the alcohol. It is not a permission to drive, and it is not a legal reading. The only safe way to drive is not to have drunk. A generous glass of wine can hold more than one standard drink.
How big is a standard drink in South Africa?
In South Africa one standard drink contains 12 g of pure alcohol, according to the South African Medical Research Council (SAMRC). That is more than the 8 g unit used in the UK and less than the 14 g used in the United States. A British “units” calculator will not match a South African drink.
| Country | Pure alcohol | Source |
|---|---|---|
| South Africa | 12 g | South African Medical Research Council |
| United Kingdom (one unit) | 8 g | NHS |
| United States | 14 g | National Institute on Alcohol Abuse and Alcoholism |
A generous pour of wine, a double of whisky and a craft beer can each hold more than one standard drink, so the hour count on a friend’s app can be too short. If you want a true count, work in grams.
How long does alcohol stay in your blood, breath and urine?
In blood and breath, alcohol shows only while it is still in you, at about one South African standard drink cleared every hour and a half; the reading falls as your body clears it. Urine can carry alcohol markers for 1 to 5 days, a blood marker called PEth (phosphatidylethanol) for 60 days or longer after chronic, heavy drinking, and hair keeps a record of months.
| Test | What it shows | How far back |
|---|---|---|
| Blood alcohol | Alcohol in the blood at the time of the sample | Now. It falls at the body’s own pace, and the NHS says this varies from person to person |
| Breath | Alcohol in exhaled breath at that moment | Now. The South African limit is set in milligrams per 1,000 ml of breath (see the next section) |
| Urine (EtG and EtS) | Markers the body makes from alcohol | 1 to 5 days, in one 2020 paper |
| Blood (PEth) | A longer-lived marker of drinking | Half-life of 2.4 to 13.6 days, and 60 days or longer after chronic, heavy consumption, in the same paper |
| Head hair (EtG) | A pattern over months, not one night | Read on a 3 to 6 cm segment nearest the scalp: 30 pg/mg or more strongly suggests chronic excessive drinking, above 5 pg/mg repeated drinking |
The urine and PEth windows come from one research paper (Drug Testing and Analysis, 2020), not from a guideline. For other drugs, from tik to mandrax, see how long drugs stay in your system.
A roadside breath test looks at the present, while hair looks back. The Society of Hair Testing defines chronic excessive drinking as an average of 60 g or more of pure ethanol a day over several months, which is five South African standard drinks every day, and a single heavy weekend is not that.
What is the legal alcohol limit for driving in South Africa?
For most drivers it is 0.05 g of alcohol per 100 ml of blood, or 0.24 mg per 1,000 ml of breath. Professional drivers have 0.02 g and 0.10 mg. Arrive Alive, the road safety site of the Road Traffic Management Corporation, confirms them. The figures come from section 65 of the National Road Traffic Act 93 of 1996.
| Driver | Blood (g per 100 ml) | Breath (mg per 1,000 ml) |
|---|---|---|
| All drivers | 0.05 | 0.24 |
| Professional drivers, as defined in section 32 of the Act | 0.02 | 0.10 |
Source: National Road Traffic Act 93 of 1996 (text as gazetted). Figures confirmed by Arrive Alive on 29 September 2026.
The Act does not say “over”. It says the alcohol in a blood specimen is “not less than 0,05 gram per 100 millilitres”, or for a professional driver “not less than 0,02”. So a reading of exactly 0.05 is already an offence.
Two more points from the same law. A separate offence covers driving “while under the influence of intoxicating liquor”, so a number under the limit does not guarantee you are legal. And a breath specimen taken within two hours after the alleged offence is presumed, in the absence of evidence to the contrary, to show the level at the time you were driving.
Is South Africa moving to zero alcohol for drivers?
It is a proposal, not a law. On 2 September 2026 the government news agency SAnews reported that Transport Minister Barbara Creecy said the government is pursuing legislative amendments to move towards a strict zero percent blood alcohol policy. Until an amendment is passed, the limits in the table above are the ones that apply.
The same report gives the timetable. The department is seeking approval from the Chief State Law Advisor and the Socio-Economic Impact Assessment System (SEIAS), to secure cabinet concurrence for the amendment by the end of 2026. Whatever is decided, 0.05 was never a target. It is the point where the offence starts. If you are going to drive, the plan that works under both rules is to drink nothing.
How do you get alcohol out of your system fast?
You cannot: coffee, a cold shower or a litre of water do not get alcohol out faster. The US National Institute on Alcohol Abuse and Alcoholism (NIAAA) says the body metabolises alcohol at a steady rate, regardless of how much a person drinks or of attempts to sober up with caffeine or by other means. Only time lowers the level.
Coffee does something else. The NIAAA says caffeine may help with drowsiness but not with the effects of alcohol on decision-making or coordination. You feel more awake and are no less impaired. The words “or by other means” cover the cold shower, the greasy breakfast and the fast walk as well. Mints, gum and mouthwash cover the smell on your breath, not the alcohol a breath test measures, which comes from your blood.
If the person you are trying to sober up is very drunk, coffee is the wrong plan altogether. Read the signs of alcohol poisoning first. In South Africa the ambulance number is 10177, and 112 works from a mobile phone.
Can an alcohol limit calculator tell you when it is safe to drive?
No. A calculator gives an estimate for an average body, and the NHS itself says clearance will vary from person to person. The law does not use your sum. It uses the specimen taken from you, and the NIAAA warns that the coordination needed for driving is compromised long before you show signs of intoxication.
So “I feel fine” and “the app says three hours” are both weak evidence. A calculator is useful for one thing: seeing how much you drank in grams, which is often more than you would have guessed.
What if you find yourself counting the hours?
If you work out every week how long until the alarm, the shift, the meeting or the school run, the drinking is setting your timetable, and that is worth looking at directly. Alcohol has become something you plan around, and a short questionnaire or a conversation can show how far that has gone.
Ask yourself a few things. Do you count on weekdays, not only after parties? Do you need a drink to steady yourself in the morning? Have you cut down and found you could not? The AUDIT questionnaire puts these questions in a scored form, and if you are reading this for someone else, the signs of alcoholism seen from outside are set out on their own page. What the drink was doing for you, and what can do that job instead, is covered in how to stop drinking alcohol safely.
If you may be physically dependent, do not answer a bad count by stopping overnight: if you have become physically dependent and need to stop drinking completely, stopping overnight could be harmful (NHS). Message us first and we tell you whether you need a medical detox. The alcohol withdrawal timeline shows what the first days look like, and what happens when you stop drinking follows the months after.
Working out why the evenings run on alcohol is the part we do with you. Ruby Weber, our psychologist, leads the psychological side of our work and has spent over two decades in the addictions field, with international and South African clients. Our resident GP does the medical assessment, and where detox is indicated it runs under 24-hour nursing supervision, with medication only when a medical professional prescribes it. Read how medical detox in Cape Town works.
Counting hours and not sure what it means? Message us on WhatsApp for a free, confidential call. Twenty to forty minutes, no obligation, and we reply the same day.
Questions people ask
For most drivers, 0.05 g of alcohol per 100 ml of blood or 0.24 mg per 1,000 ml of breath, under section 65 of the National Road Traffic Act. The law says “not less than”, so reaching the figure is already an offence. A zero-alcohol limit has been proposed but is not law.
A breath test reads the alcohol in your breath at that moment, so it falls as your body clears the alcohol. There is no fixed number of hours: the UK National Health Service (NHS) says clearance varies from person to person, and it depends on how much you drank. The South African breath limit is 0.24 mg per 1,000 ml.
It can. EtG (ethyl glucuronide) and EtS (ethyl sulfate) are markers the body makes from alcohol, and one 2020 paper puts their window in urine at 1 to 5 days, much longer than a breath test looks back. It is one study, so the range is a guide only.
Yes. For professional drivers as defined in the Act it is 0.02 g per 100 ml of blood and 0.10 mg per 1,000 ml of breath, well under the 0.05 and 0.24 that apply to other drivers.
No. The NIAAA says the body clears alcohol at a steady rate whatever you try, caffeine included. Time is the only thing that lowers the level.
Where can you get help in Cape Town?
Message Renewed Life Center in Cape Town on WhatsApp and we set up a free, confidential call: twenty to forty minutes by WhatsApp, video or phone, with a reply the same day. Admission can be immediate and typically happens within three days of first contact.
On the call we ask what you drink in a normal week, for how long, whether you have tried to cut down and what happened when you did, and whether stopping has ever made you shaky or ill. You leave the call with a working answer on detox, the part of the programme that fits and a likely arrival date, and the clinical assessment within three days firms it up. Nothing is decided unless you want it to be.
You do not have to be sure that it is a problem, and a relative can make the call for you. Kerry Dominie-Williams, a TRE (tension and trauma release exercises) practitioner at the centre, says what matters at the start: “Willingness is the key.”
This article is general information, not medical advice.
Sources
- National Road Traffic Act 93 of 1996 (gov.za)
- Arrive Alive, alcohol and driving limits
- SAnews, 2 September 2026, zero blood alcohol policy
- South African Medical Research Council, Creating a safer drinking environment
- NHS, Calculating alcohol units
- NHS, Alcohol support
- NIAAA, Defining how much alcohol is too much
- NIAAA, The truth about holiday spirits
- Drug Testing and Analysis, 2020 (PMC8406557), alcohol biomarkers
- Society of Hair Testing, consensus on hair testing for alcohol, 2019
- Western Cape Government, emergency numbers
If the drinking sets your timetable, talk to us.
Medical detox with 24-hour nursing supervision where it is clinically indicated, therapy in the same house, and admission that can be immediate, typically within three days of first contact.
Free first conversation of 20 to 40 minutes, by WhatsApp, video or phone. We reply the same day.
Leave a request for consultation
Tell us a little about the situation. The first conversation is free and confidential, and we reply the same day.