Can a water filter render urine drinkable?

This theoretical question was inspired by the incredible courage of Aron Ralston. In his account of his ordeal, he mentions thinking that maybe he should save his urine for possible consumption when all his water had run out. My question, then: In the event of a life-threatening situation, could one use a water filter to filter the impurities out of one's urine, thereby rendering it fit to drink? I realize this is kind of a gross question, but the theoretical alternative (dying of thirst in the wilderness) is even grosser... Bill Charlottesville, Virginia

A: OK, the gross-out meter just topped out at ten. But what the heck, it's a valid question. And Aron Ralston didn't think about saving his urine, he did—and drank it. As he writes in his book, Between a Rock and a Hard Place: "Sip after sip of acidic urine has eroded my gums and left my palate raw."

MiniWorks EX

@#95;gui_include name="ad_in_article"@#95;gui_include
In any event, drinking one's own urine is hardly unheard of; in some cultures, in fact, it's fairly common (sadhus in India, among others, drink it). Hippocrates advocated it 2,500 years ago. And in some homeopathic circles a sip of urine is seen as a way to stimulate the immune system. Moreover, there's nothing inherently dangerous or "wrong" with it. Fresh urine is sterile—no bacteria or viruses after the kidneys have filtered out all that crud. It does contain uric acid, which is what caused Ralston's gums to become sore.

However, if one is in an emergency pinch and begins to "save" urine in a bottle for later use, then the stuff can begin to breed bacteria (question: If you're in such dire straits, does it really matter?). It's also true that you're going to gain very little real benefit from drinking urine to stave off death by thirst—you'll be producing such a tiny amount, it's not apt to make any real difference. You really need close to a gallon of water a day to maintain good bodily health; more if you're working hard. And there is that law of diminishing returns; after all, urine is a waste product designed to rid the body of the materials it doesn't need.

But—and here's the nub of your question—what about filtering? My response: Why not? It may help remove any bacteria that have developed, and if it's a carbon-based filter such as the MSR MiniWorks ($79; that will help remove the acid component and even improve the, um, flavor.

Excuse me. I have this sudden urge to get a glass of clean, cool water...

Read "Trapped", an exclusive excerpt from Aron Ralston's new book featured in the September 2004 issue of Outside.

Our mission to inspire readers to get outside has never been more critical. In recent years, Outside Online has reported on groundbreaking research linking time in nature to improved mental and physical health, and we’ve kept you informed about the unprecedented threats to America’s public lands. Our rigorous coverage helps spark important debates about wellness and travel and adventure, and it provides readers an accessible gateway to new outdoor passions. Time outside is essential—and we can help you make the most of it. Making a financial contribution to Outside Online only takes a few minutes and will ensure we can continue supplying the trailblazing, informative journalism that readers like you depend on. We hope you’ll support us. Thank you.
Contribute to Outside
Filed To: Filters and Purifiers
Lead Photo: courtesy, MSR
More Gear