Instructables

How to make a life saving straw?

How do you make a life straw that can filter water?
It's a survival device that some people carry in their backpack. 

I tried to make one using this home made water filter but it's not enough according to the author. I tried to filter some turbid water that used to come from our tap water during rainy seasons and it didn't work.

I have a big packet of charcoal pellets with me now and no use for them. Can someone give an idea how to construct the life straw ? Or what are the other uses for charcoal pellets?

Regards,
RS

orksecurity4 years ago
Ordinary charcoal can't be trusted for this purpose. Even activated charcoal (which is what's used in charcoal based filters) will only remove some contaminants, and shouldn't be trusted as a safety device.

If you really want it to work as intended, I'd buy rather than trying to homebrew. In a true emergency situation, where you don't have a professionally-made filter, boiling is probably a better solution -- it won't remove chemical contamanants (unless you actually distill the water; see many descriptions of survival stills)  but it will kill the diseases that are more likely to be an immediate problem.
 Activated charcoal will remove a lot of organic compounds, so may improve the taste of water, but it will not sterilize it, nor will it get rid of everything.

Water is made turbid by particles of different sizes.  Larger particle (still too small to see) may settle out after a few minutes.  The tiny ones have to be removed by filtration.  The "home made water filter" guy uses fish-tank fiber for the larger stuff (it doesn't swell like cotton and jam the filter)--he says the charcoal gets rid of particles too, but I'd think it would have to be packed tight, which would make it slow.  I'm not sure his filter removes turbidity

You can try different things to get rid of turbidity-- clean sand will work if the column is long enough.  You can read about water purification at http://en.wikipedia.org/wiki/Portable_water_purification 

After filtering, water still has to be sterilized.  The "life straw" ref mentions using a resin with iodine, which sterilizes the water. The water probably tastes of iodine too.


rseni (author)  cyberpageman4 years ago
For a life saver, I guess yes, it's better to buy one. The only problem with these devices and filters is that they have a limited lifespan. Otherwise, buying them isn't bad even at a high price. 
Hi,

Bit late for this thread but I would use something like a Katadyn water filter.
I've used their small ceramic water filter for the last 20 years whenever I go on holiday to places where the water is suspect.

It works by forcing the water through a ceramic cartridge - bit of manual work involved but I don't mind that. I chose it when planning a trip to the Sahara - it was (and still is) the simplest, most reliable and long-lasting device I've seen.
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