Drinking your own pee for survival: does the science bear it out?

If you’ve been on the internet for a minute, you’ve no doubt seen the famous Bear Grylls meme. But long before the British Army SAS veteran guzzled his way to meme glory in a now-infamous episode of his “reality” TV survival show, drinking your own pee was a classic metonym for desperation in prepper/survivalist folklore.

Of course, survivalists aren’t the only group with a bit of a pee drinking obsession. The practice shows up in ancient ayurvedic teachings, and has been espoused by modern athletes.

Given that urine is a bodily waste product commonly regarded as repulsive, why the desire to drink it? Well, leaving the fetishists aside, humans are curious, and we’ll give just about anything a try in case it turns out to be useful. Even practices that aren’t useful (spoiler: drinking pee is not useful) can manage to stick around, as long as the activity in question doesn’t immediately, obviously harm its practitioners. Note that people who drink their urine for whatever reason are hydrating normally with ample water, so these practices aren’t quite comparable to survival pee drinking.

To be fair, urine did have quite a few uses historically, the most ingestion-related one being teeth-whitening (due to the ammonia in pee). If you’re tempted, there’s a cocktail guide, which includes this essential tip: “[D]on’t collect the ‘head’ and ‘tail’ of the stream, only the middle, due to the fact that more impurities may be contained in the first and last parts of the stream. I think that’s an important point which everyone agrees on.” Naturally.

Here’s what you need to know:

• There’s no health benefit to drinking urine, at least none that science has identified.
• It’s mostly made of water, urea, and salt, plus some other trace “ingredients.”
• In a survival situation, drinking pee won’t help much.
• The amount of harm drinking urine will do depends on how dehydrated you already are. The more dehydrated you are, the more dangerous.
• You need to do reverse osmosis or distillation to properly filter and purify urine.

Drinking your own urine is pointless

It turns out that even in a life-or-death situation (probably… more on this momentarily), drinking your own urine is sort of the survival equivalent of slacktivism — it feels like you’re Doing Something about The Situation, but you really aren’t.

Despite the example set by Bear Grylls, or Aron Ralston of amputated-his-own-arm fame, drinking pee — whether it’s yours or someone else’s — is like drinking seawater. You will be ingesting liquid, sure, but it won’t slake your fundamental thirst.

The Urine Metabolome database lists thousands of substances that show up in urine, but for the most part it comprises water, urea, and salt. Contrary to popular opinion, pee is not biologically inert, but neither is it notably dangerous (although, uh, consume at your own risk). Dr. Jutta M. Loeffler explains in the Pan African Medical Journal:

Urine is sterile where it is produced in the kidney, but once it has left the body, it is usually contaminated. It is not toxic per se. There may be rare situations where urine is the cleanest liquid at hand to pour over a dirty wound, or the only liquid to drink when buried under a collapsed building or lost at sea for days, but most of the time there are better or tastier ways to improve one’s health.

You may notice Loeffler’s implication that if you are buried under a collapsed building or lost at sea for days, there might be some benefit to urine consumption. This notion is echoed by a random hospital in Winchester, MA… not that their endorsement is enthusiastic:

When faced with life-threatening dehydration, drinking urine may make some sense, since the temporary benefits are likely to outweigh the risks. However, this last ditch effort will be short-lived, since the kidneys stop making urine as the dehydration worsens.

So drinking urine won’t be much help, but hopefully it won’t kill you a heckuva lot faster than the preexisting threat.

All of that said, other sources insist that you shouldn’t sip the golden juice even if you’re worried that it’ll be the last liquid to pass your parched lips. Outdoor gear producer Mountain Safety Research advises against pouring pee down the hatch under adverse circumstances, warning that it “will have the opposite effect and dehydrate you at a faster rate.” Furthermore:

It’s important to remember that urine is your body’s vehicle for eliminating liquid and soluble waste. Though mostly water, urine contains dissolved salts, minerals and trace amounts of toxins from your liver. The more dehydrated you are, the higher the concentration of these pollutants in your pee. If you’re in a survivalist situation, you’re likely extremely dehydrated and the concentrations are very high.

At this desperate point in time, drinking your urine — and putting those pollutants back into your system — can cause a build-up of toxic levels. It’s for this same reason that it’s so dangerous to drink seawater. The more you drink, the faster it dehydrates you. The (very-simplified) science is: too much salt draws water out of your cells through the process of osmosis.

The bottom line: drinking your own pee in a survival situation probably won’t help, and there’s some reason to believe it may leave you with some permanent damage if you ingest it when you’re really dehydrated.

What about filtered urine?

Mountain Safety Research also warns people not to rely on simple filtration:

The dissolved salts, ions and molecules, like urea, that are present in urine are too small for backpacking filters and even purifiers to remove. Other forms of treatment, like UV light or chemical treatments only kill the microbes; they do nothing to rid the water of these other molecular-sized contaminants.

The only way to safely drink urine (such as in a survival situation, as your only water source) is to remove those dissolved contaminants from it, or at least bring them down to a negligible level. There are only two ways to do this. One is reverse osmosis, which uses extremely high pressure to force water through a membrane that literally passes only water (not even salt). The other is through distillation — essentially evaporating out the water molecules and letting them condense again in a different vessel for drinking.

This is echoed by revered filter brand LifeStraw, which cautions: “LifeStraw filters do not remove dissolved salts and are not designed to be used to drink non-diluted urine. Because of this, we do not recommend drinking urine with the LifeStraw in even low amounts.”

As MSR notes in the quote above, it should be safe to drink if you distill it — this is what the SAS Survival Handbook recommends.

So unless you’re a prepper interested in a full-on greywater filtering and distilling system, your own urine (or that of your neighbors, we don’t judge) won’t come in handy in a disaster.