This question was inspired by watching one of the Pirates of the Caribbean movies; particularly where Jack Sparrow allegedly survives on a desert island by finding an unlimited supply of rum. I've heard alcoholic drinks dehydrate you more than hydrate you, so this seems like an unsustainable strategy.

My question is threefold.

  1. How long can a human survive by drinking hard liquor (40% alcohol by volume) for their sole water intake (ignoring food)?
  2. If it's unsustainable, what will finally take you down?
  3. If the hard-liquor approach isn't viable, what % alcohol can keep you hydrated (beer, wine, etc.)?

1. Question on dehydration studies
2. Question on what dehydrates

  • 5
    $\begingroup$ I would say that the main problem with high percentage alcohol is that it is a cytotoxic substance which will not do good. $\endgroup$
    – Chris
    Apr 22, 2015 at 20:20
  • $\begingroup$ There are a lot many things that can happen because of excessive alcohol consumption. First of all the gut will be affected. Excessive drinking can also cause palpitations $\endgroup$
    May 30, 2015 at 17:15
  • $\begingroup$ One reason this is too broad is there are many ways of drinking alcohol - three tots in a row, spaced out over an hour, etc. - and these things matter when you're dealing with a toxin. Also, the rum he was drinking was probably greater than 40%, especially if it lasted that long. $\endgroup$
    – Amory
    May 31, 2015 at 1:22

2 Answers 2


I commented above that it will depend heavily on at what pace you drink your rum, but in short, no, no you cannot. If you do it quickly, you'll die of alcohol poisoning, and if you drink it slowly, you'll probably die of dehydration[1].

io9 summed up some research a few years ago, the majority of which is largely bunk. One study (ncbi, free pdf) however, from 1996, claimed to find that:

These results suggest that alcohol has a negligible diuretic effect when consumed in dilute solution after a moderate level of hypohydration induced by exercise in the heat. There appears to be no difference in recovery from dehydration whether the rehydration beverage is alcohol free or contains up to 2% alcohol, but drinks containing 4% alcohol tend to delay the recovery process.

So stick to (American) beer.

Sidenote: In Belgium, they divide their (truly excellent) beer into two categories: special, which are stronger and often bottled, and thirst-quenching, which have a lower alcohol content and are often had with lunch.

[1]: Citation: Personal experience and the story of Johnny Tarr.


Interestingly enough, the mainstay drink in the Middle Ages (medieval times) was "small beer" (cheap low-quality beer with low alcohol content). Back then there was no concept of water purification and treatment - most of the water in a town or city back then would be loaded with pathogens and considered unsafe/unsuitable for drinking. The alcohol in "small beer" was enough to eliminate most of these pathogens while dilute enough to be used almost like water.

However, health problems quickly start as the amount of alcohol increases. As Amory mentioned, 4% alcohol weighs on dehydration recovery. There's no way anyone could survive on a desert island drinking only 40% alcohol hard-liquor or similar.

No matter if the rum is spaced out over time or consumed like water, it's a non-solution. Spacing it out over time and allowing proper detoxification over time will be insufficient to keep up with regular water needs; drinking it like water will quickly cause lethal alcohol poisoning.

  • 1
    $\begingroup$ Beer contains roughly 5% alcohol. This isn't anywhere near the concentration to kill most of the pathogens possibly present. Beer was interesting, because it is boiled in the process and is thus less likely to be spoiled than pure water at that time. Additionally it would be great if you could add sources to all of your answers. $\endgroup$
    – Chris
    Aug 15, 2017 at 20:46

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .