If you’re an outdoors person, one of the earliest things you learned was probably that in-field water sources can’t always be trusted as drinkable. A clear mountain stream could have a dead sheep in it just upstream, for example. Maybe you learned to boil it, or perhaps add chemical tablets. Up-to-date campers have a range of filters at their disposal thanks to nanotechnology, but such devices aren’t the only options to avoid sickness. [BeraAjan] has built one using plant xylem.
The inspiration for this filter came from an MIT paper, and the plant xylem in question isn’t the thin layer we were expecting but a far thicker one found in young conifer branches. In fact, the whole twig without its bark is placed in a tube, and the water filters through it.
It’s fair to say that this isn’t the fastest of filters though, as you can see in the video below the break. He’s combined a few individual filters, but maybe it’s not for the easily bored.
Header image: USFWS, Public domain.
I could take toilet paper and do the same. (But the water would not be taste like pine)
Where is the qualitative analysis that is filters anything ? Or is it just a MIT inspiration of anything at all ?
My body consumes water faster than that contraption can deliver it.
And…
Where in the north woods will I find a half coconut 🥥 shell?
(an African swallow perhaps? )
B^)
So make ten. This is about improvised survival, and it’s composed of forest trash; scale as needed until you aren’t at risk of dying.
Use your knife to carve one out of piece of tree and scale the whole thing up x10 for your requirements.
The device described in the paper feeds water at 5 p.s.i. and works much faster.
that equates to about 0.3 bars, which is equivalent to a height of about 3 metres of liquid above the filter unit. So the contraption in the video could easily be adapted to that, granted the filling of the container becomes a pain.
Interesting. I read somewhere that even passing the water through a clean cloth reduced cholera instances by 50% in trials in India.
I wonder if they controlled for the tendency of the clean cloth observers to reject water with bits of poop floating around in it
Cloth reduced risk of guinea worm by 100%
*Bear grills and his urine soaked socks enter discussion*
Considering hindus take cleansing baths with corpses floating around them, its not hard to imagine how little filtering is needed to massively cut down on pathogens.
Similar to “Primitive Technology” where he filtered water through cane vines.
https://www.youtube.com/watch?v=nG-rNHgFxhs
I love his channel, I really like the episodes where he smelts iron using primitive techniques.
yeah sorry but no that’s not how xylem works i don’t buy it. will it filter out microscopic debris sure but the tracheids are way bigger than microbes and are not designed to conduct water primarily sideways through the pits as suggest in the article. my guess is faulty methodology and they simply squeezed the wood so much that the conductive surface basically shrinked to zero in effect creating a microscopic filter.
in addition if you need tubing and some decent pressure to make it work this has absolutely zero value in and outdoor or emergency situation.
I don’t buy you not buying it. In a survival situation, is squeezing it against the law? Is it not better than drinking completely unfiltered water, removing most of the debris and vectors of disease if not all? We’re talking about survival, so these are people with no other options.
I put a plant based filter in my morning beverage device, followed by fermented, dried, roasted, then ground tree seeds and then put boiling water through it all. Pretty tasty and likely microbially safe because of boiling (except for things like those pesky prions).
I was unaware of those tree seeds containing prions.
If you’re near conifer trees, there’s a really good chance that you’re somewhat near pretty good water, and you also have a good source of fuel to boil it.
Even if you have no way of boiling, dig a pit at least 6 feet away from a lake, pond or stream, and the water that fills it will have passed through at least 6 feet of soil, enough to filter out almost anything bad in the waterbody.
My goto in the woods is an Ultraviolet light. It’s fast, easy, and doesn’t fail silently if it freezes (the bane of physical filters). If that ever fails, I have several ways to light a fire or stove to boil water. My emergency kit contains both a lighter and waterproof matches, neither of which I’ve ever had to use because a flint and steel has never failed me yet. In an absolute emergency, my first aid kit contains an antiseptic (Povidone Iodine) that can be used effectively to purify water.
This sounds reasonable enough at the core – let a plant filter your water for you – although not in specific or if you’re trying to find specific supplies like these. Also if you’ve got coconuts or some kinds of cacti, you can drink from them instead. But regardless, it also has to be balanced against $20 artificial hollow fiber filters like the sawyer mini. They will last an incredibly high number of gallons while being very safe, so long as you keep them in your inner pocket if there’s a chance of them freezing.
I believe MIT developed a project page with design information (http://www.xylemwaterfilter.org/), and after having read three of the relevant papers, their filters perform okay. They can filter out most bacteria, but struggle so far as viruses and the smallest cells are concerned. Performance can fairly be equated to a “LifeStraw” or other plastic membrane filter but not to the best ceramic filters or reverse osmosis. Note that it is not untreated wood, but has to be boiled in alcohol.
(I’m rather surprised I haven’t seen mention of this on Hackaday before now. The project had many field tests in India and has been covered by YouTubers such as Primitive Technology, whose video was mentioned in another comment above.)