The hot sun is boiling your skin and blood. The circling gulls look like vultures. You lick your chapped lips, wishing you had some water to drink. Then a voice of some bygone TV survival star echoes in your mind, “Might as well drink my own piss.” Drinking urine while on a lifeboat will not save your life, even if you might have heard about people surviving that way before.
Just like you are warned to never, ever drink seawater that has not be desalinated, you should never drink your urine. If you are lucky enough to have a solar still on the lifeboat, that is the only way your urine becomes drinkable; but when you are shipwrecked, will you really remember to pack supplies for a solar still? Probably not.
Just because Gandhi did it, Bear Grylls does it, and a man trapped under rubble in China after an earthquake survived by drinking it, does not mean you should do it.
Drinking urine is generally a bad idea, no matter where you are. The more dehydrated you become, the more concentrated your urine is with toxins the body is trying to rid itself of. Plus, urine has a lot of salt. Though your pee is not as salty as the ocean, drinking any type of saline liquid while sitting beneath unmitigated sun is asking for trouble. Remember that urine is the body’s “vehicle for eliminating liquid and soluble waste” (MSR Summit Register, 2016).
Urine is mostly water, but it is also full of dissolved salt, minerals, and contaminants filtered out by the kidneys. Drinking urine when you are already dehydrated means reintroducing pollutants into your body that will tax your already exhausted system, causing a buildup of toxins and the potential onset of septicemia.
Even the Army Survival Manual (1999), Chapter 7, discusses what not to drink when trying to survive: “Do not drink urine, fish juices, blood, sea water, alcohol, melted water from new sea ice.” Urine is the first thing listed.
So when it is okay to drink your urine? Only when you are adequately hydrated and the color is a pale yellow or almost clear. In this case, the urine is mostly water with very few dangerous microbes in it. Still, there will be trace amounts of salt, ions, and molecules, like urea dissolved into it. Since you cannot filter these out using primitive means like activated charcoal, you would have to boil or distill it. But it will still smell like urine and have an aftertaste.
In short, never drink urine when trapped on a lifeboat, because you are drinking toxin-concentrated saltwater. Never drink urine unless in a dire situation where you cannot procure hydration, such as getting trapped beneath rubble. Otherwise, attempt to build a solar still for fresh water or boil your urine first before gulping it down.