It's a fact frequently shared at parties and across social media: urine is sterile, so you should drink it if you find yourself in a waterless pinch. But like so many cocktail party factoids, this one is absolutely not true. Urine ain't sterile, friends, and neither is any part of you.
Microbes are an indelible part of our bodies and the world around us. Not even the uterus and placenta, long thought to enshroud fetuses in sterile envelopes during gestation, are actually germ-free zones. They contain complex, varied microbial colonies—microbiomes—that help prepare us for the real world.
But it's apparent that many doctors are still under the impression that urine is sterile (unless someone has a urinary tract infection). That's likely a holdover from the days when bacteria in the body was thought of as a negative thing—the source of infections—as opposed to the complicated garden we now know to exist within us. It would be absurd to assume that a healthy urinary tract has absolutely no bacteria in it, given the abundance of microbes throughout our body. In fact, research indicates that replenishing the "good" bacteria found in the vagina can help prevent or treat urinary tract infections—so it seems likely that these friendly bacteria often traffic there.
So even if urine was sterile at some point, you better believe it's teeming with microbial life by the time it finishes its journey to your toilet (or wherever you're putting it).
Okay, so, to recap. Urine: not sterile. But on the other hand, bacteria: not inherently bad. So if you don't have a UTI, is drinking your urine okay?
Lots of folks drink their own urine for the supposed health benefits (which, for the record, are totally unproven). Others rely on urine during emergency situations out in the wilderness, and still others consume it for more, ahem, personal reasons. But it's not a great idea: even when you're healthy, urine contains salt, which will dehydrate you. If you're drinking urine because you're dehydrated, the salt concentration will continue to increase every time it goes through your body. You're basically forcing your kidney to re-filter the substances it voided in order to keep your body healthy, and it should go without saying that this isn't a great idea.
If it's a true emergency? Drinking your own urine is probably okay for a day or two. Any longer, and you risk over-taxing your kidneys and falling into deeper dehydration troubles. But unless you're sweating buckets, you can go three days without drinking any water at all. So maybe you shouldn't turn to pee just because you're feeling parched.