Going off the deep end – urine filtration in the backcountry?

[Roger Caffin]

Hi Kat

Fair enough. Trees need a lot of water. Sounds good to me.
Yeah, we have a lot less soil here. Some of our paddocks have only a few inches of soil, and being the Aus summer they are bone dry. (We did not make the paddocks: they were here when we bought the property.)

Cheers

[Rex Sanders]

Apparently every drop of the Santa Ana River in Southern California is “recycled” 7 times before it gets to the sea – and that’s with mostly underground flow. It’s interesting to map the water intakes and sewage treatment plants for each major city along the river. Water intake is carefully located upstream just within city limits, while the treated sewage is dumped back in the river downstream at the city limits.

This pattern is repeated all over USA, and probably elsewhere.

Back to the original topic: There’s no practical way to turn urine into drinking water while backpacking. Astronauts don’t have much choice, and money is almost no object.

— Rex

[Rex Sanders]

More on the “water for astronauts” tangent: The Apollo astronauts drank water generated as a byproduct of hydrogen-oxygen fuel cells, rather than reclaiming urine. Urine was vented into space.

In the Apollo 13 accident, one of the fuel cell oxygen tanks exploded, and took out the other, redundant fuel cells. Among many other critical problems the astronauts also had to ration water, limited to 6 ounces per day. Fred Haise returned to Earth with a serious urinary tract infection, caused in part by not drinking enough water.

How does this apply to backpacking? With more backpackers carrying more electronics needing more power, hydrogen-oxygen fuel cells almost make sense (well … not really). With the correct design, you might get some water too.

— Rex

[MJ H]

In open country, you could tether a large hydrogen-filled balloon to your pack. This would take weight off your back and, at the end of the day, you could use the hydrogen to react with the oxygen in the air to heat your food and recharge your electrics.

[Ian]

Just tried filtering my pee through a Sawyer filter.   At first taste it’s slightly better than the “beer” Tom drinks but I still can’t recommend it.

[Roger Caffin]

Are we talking about a standard filter – one designed to remove bacteria and protozoa? Such a filter cannot remove dissolved matter, and pee is usually clear with no particles.
So I don’t see the point of the test.
(Yes, I know I am pedantically nit-picking – so?)

Cheers

[MJ H]

Somebody should try it with a Steripen. For science.

[Lyle G]

Steripen just uses UV to sterilize your water by killing microorganisms. It can’t remove salts or ammonia to recycle urine. Not sure if you were joking.

Source: I’m an actual scientist, although I don’t work on water treatment I do work on some tangentially membrane/filtration related projects.

[MJ H]

I knew never finishing the PhD would come back to bite me in the ass.

[andrew mitchell]

I am an Emergency Doctor. Urine is safe and sterile but is too concentrated of toxic wastes to do any good unless diluted at least 2 to 1. Maybe the astronauts distilled the wastes out. Same with sea water.

[Mark Baker]

Can some provide a good explanation of how those portable saltwater extractors work that are in sailboats that provide drinkable water in more detail.  What is the smallest unit available (just curious) and if that would work with urine.

Thanks…

 

[Josh Leavitt]

Your kidneys already recycle your pee, at least they do if everything else is working right: http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/hypopit/adh.html

But I would be interested to see if we can improve the efficiency of this by taking Desmopressin? There has to be some college kids here who have taken this, I hear it is the new Aderal.

I await the test results………..

[Terry Sparks]

From a safety and practical point, recycling your pee to use as drinking water could end up putting yourself at risk on the trail.  Being you don’t know how much pee you’ll have at the end of the day to recycle and, with desert hiking you can’t assume you’ll never get off trail or your route, forcing you into hiking additional  miles to your next water source, I don’t see this as a viable option.

I’ve hiked a good amount in the desert, including thru- hiking Death Valley, Death Valley thru to Joushua Tree, thru-hiked the PCT and now 600 miles in N. New Mexico on a CDT thru, I use a Wet Sham Wow under my hat for warm weather hikes.  The Sham Wow stays wet for upwards of two hours when dunked at a water source when under a hat and only requires a few ounces of water to re-wet afterwards.  I can also say with confidence that it cuts my water intake by as much as 40-50% on these desert/warm weather hikes.

If you’re looking to cut water weight, this is a practical and safer way of doing so.

[Tim Hawthorne]

There is a lot of total dissolved solids (TDS) in urine.  Many could be dangerous to the human body if not limited.  The two methods used for treating tds is evaporation/distillation and membranes at higher pressures.  Both require a significant amount of energy.  As an engineeringician, I have designed both systems on very large scale.

Recently, I have been working with a solar stove that weighs 2 lbs. and boils two cups in 40 minutes. I collect it in a plastic funnewith a long plastic hose.  I can make about a half of cup of distilled water using two cups of non potable water.  It is slow but works.  If it could work well and stay aimed at the sun as you hike it might have potential. Have not tried it on urine, and probably won’t.  I still like to carry plenty of water.

[Marcello]

I’m with you on that…Don’t put yourself in that situation. catching dew or condensation is nothing new. Do your research. It’s
hard to believe that anyone would want to drink what you body is getting rid of. Too much time on their hands…get out and hike!!

[Marcello]

an engineeringician… That’s funny!Love it

[Adam O]

Filtering urine requires removing any ions from the solution.  Methods that we use to do this are:

-reverse osmosis (hydraulic pressure forces water through a membrane)

-forward osmosis (osmotic pressure forces water through a membrane)

-biochemical reactor (what spacestations use, bulky and slow)

-nanofiltration (hydraulic pressure forces water through a membrane, only partially effective, usually uses as a pretreatment for other methods)

-thermal distillation (boiling water, heat can be provided by electricity, geothermal, or fuel for quick use and sunlight for slow use)

-vacuum distillation (boiling water by using ultralow pressure produces by an air pump)

-freeze thaw (exactly what you think it is)

-membrane distillation (utilizes a temperature gradient to move water through a membrane)

-electrodialysis (uses an electric field to move ions through a membrane)

-chemical deionization (ions stick to chemical beads which are periodically replaced)

Most of these are slow and require huge amounts of energy.  If this wasn’t the case the water shortage crisis would be solved in an instant worldwide.  This also of course makes them completely unpractical for backpacking. Chemical deionization does not require lots of energy but it is slow, bulky, and heavy.  The same is true for biochemical reactors.  Solar distillation is far too slow.  That just leaves forward osmosis.  This is somewhat practical for backpacking use but nobody sells such a device.  The membranes are hard to produce, foul quickly if not regularly treated, require you to already have some clean water to start the reaction, and do not produce pure water.  You need to add a chemical, usually sugar, to the mix to create the osmotic pressure.  Also it’s sssllllooowwww.  Keep in mind that you only pee out some of the water you intake.  Some comes out with your poop and some is sweated out.  So you’ll still lose water over time since you can only “recycle” some of it from your urine.

[Brad P]

People drink Budweiser, so why not?

[Alan Lau]

I am in agreement with Dave Thomas as well as Alexander S.  I too, am a nephrologist.  Your kidneys remove toxins from your blood stream and dump them into your urine.  If you drink your own urine, you basically have 0% kidney function in terms of removing waste products from your body.  If you continued to do this for a week you probably won’t survive.  It is true that we do ingest molecules from other people, but as Dave pointed out, when we do this the quantities are in far smaller concentrations compared to drinking your own urine.  Unless you can separate the water from the dissolved chemicals/minerals, (in this case a solar still)  I don’t think drinking your urine is a good idea.
Could you do this for a day or 2 and survive?  mmmmmm probably, depending on the circumstances.

[MJ H]

Isn’t wandering off into the desert, running out of water, drinking your own urine, and making it back barely alive how the Australian interior was explored? I’m not saying it’s a good idea, but tradition matters.

[Author]

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