Are there lightweight solar stills that work?

May 26, 2008 9:47 PM

Does anyone know of a super lightweight (i.e. backpackable) solar still that could be used to purify sea water on a long trip?

I'm thinking something that could be set up using trekking poles or sticks maybe...

I'm toying with the idea of a there-and-back desert trip to the ocean, and it would be nice if I could carry half of the water I need for the whole trip, and purify enough seawater for the return trip while I'm near the ocean. But it seems like a long shot to end up with surplus water out of this thing without waiting around for days.

I've googled some stills that can produce about a gallon a day, so the question is whether I could get comparable production with something really lightweight.

posted by Dr. Send to sports, hobbies, & recreation (7 comments total)

That's quite a gamble you are taking with the weather - what if it's sunny when you get there? One gallon a day is cutting kinda close too, even if you could miraculously pull a gallon out of your still. If you use a fuel driven still, there still alot of weight there too. There's really no good solution for this type of problem that's not ridiculous expensive.
posted by bigmusic at 10:58 PM on May 26

eh that should read "what if it's NOT sunny"

I feel your pain on this, I want to hike the length of the Padre Island seashore - but the water problem is one that keeps me from evening seriously planning it.
posted by bigmusic at 11:22 PM on May 26

Coincidentally, I just heard about solar distillation in relation to the Watercone. Unfortunately for you, the maker of the Watercone is not selling individual units. And the makers of the Solar Solutions Aquacone have discontinued it. There is this one for $150, which is a little cheaper than the one bigmusic linked to.

I'd suggest you just build one. You take a black circular tray, a plastic cone and a bundt cake dish and voila! I like the design of the watercone best, but you could even try this design (the "first model"), which seems very simple and might suit your needs more.

Depending on how arid the environment is on your way out to the ocean, you could use this type of solar still to keep your water supply from being completely depleted by the time you get to the shore. It would also cut down the total amount of water you would need to distill from the sea.
posted by HE Amb. T. S. L. DuVal at 12:15 AM on May 27

Maybe you should try to carry all your water instead. Many long distance trekkers have had good luck with a two wheeled cart they drag behind them. Jon Muir (not that one) walked across australia with one. His was pretty basic and home brew; there are others that have good clearance and use bicycle tires. If the terrain is right, I'd think you could do quite well with a cart. These guys make a cart that might solve the problem.
posted by thenormshow at 6:21 AM on May 27

For a mere $3500 plus the trouble of lugging around another 45 lbs or so of equipment you could take a 1.5gal/hr electric water maker and an 80W solar panel to power it. That same 45 lbs amounts to about 5.5 gallons of fresh water, so depending on how much water it would save you from carrying it might be a net savings, weight-wise, but probably not by much unless this is a seriously long trek.
posted by jedicus at 9:40 AM on May 27

It's non-solar, but fwiw Graham Mackintosh writes about how he used an aluminum kettle and some copper pipe to distill seawater for his Baja walk.
posted by anadem at 11:16 AM on May 27

Thanks for all the replies.

I really like those cone-shaped floating stills that HEATSLD linked to, and making one (or more) probably wouldn't be that hard. It also seems like if production was falling behind, one of those cones could be used in conjunction with a stove or a fire to distill a lot of water in a hurry.

Now I just need to figure out how to quit my job...
posted by Dr. Send at 5:04 PM on May 27