I was listening to a BBC world report on 3rd world technologies, and heard about a simple method to" clean dirty water of bacteria, viruses and Micro organisms". Given the recent post on Puritabs, it seems like a good emergency alternative:

1/ Half fill a clean plastic bottle of the water you wish to drink.
2/Shake vigourouly for 20 seconds (with cap on <img src="/images/graemlins/smirk.gif" alt="" />) to oxygenate the water.
3/ Top up the bottle with more water.
4/ Leave in sunlight for 5-6 hours
5/ Drink

Ok, it might not be the long cool drink you were craving, nor be suitable for all conditions, but useful knowledge nevertheless.
Any comments?

IIRC, this has already been mentioned in a thread on this forum..... a search may find that thread, which contained a few intersting links...

Yes your right...sorry folks <img src="/images/graemlins/blush.gif" alt="" />

no need to be sorry <img src="/images/graemlins/grin.gif" alt="" />

I know there were several threads but up to now have found only this one

It takes several threads to weave a tapestry <img src="/images/graemlins/wink.gif" alt="" /> I would improve on this method by tossing in a teabag. It's called called suntea and iced. Said result, recalling the indignant remarks of an expatriate Mrs Doubtfire lookalike should be ignored by our G.B. contingent <img src="/images/graemlins/tongue.gif" alt="" />

I know we discussed this before but I still have trouble trusting this method. I wish I could find some scientific studies from a reputable source to prove this. I mean heck, if all you have to do is put water in a clear container, shake it and leave it in the sun for 5-6 hours then why isn't this a more widely accepted method??? <img src="/images/graemlins/confused.gif" alt="" />

There is scientific evidence - but there's more to it than what was posted here. Somewhere in the old posts... I posted a link or two to this in the past. Google it and you should find some more detailed info.

The reason it's not widely accepted is that the conditions when it works aren't always there. It has to reach 160 degrees for a certain amount of time. Think that's going to work in Minnesota this time of year? Not a chance. You need some way of confirming that it reached 160.

Ah now that is a lot more believable and makes a lot more sense to me. Thanks... 160 degrees for 5-6 hours would be difficult to achieve even on a summer afternoon here in Texas. Now I understand more why the corregated steel roof was used as an example in the other post which also used South America as a setting.

I don't think it's as long as 5-6 hours, maybe only an hour or two. But I don't remember for sure, and I'm not absolutely certain the temperature is 160, but it's something like that. I also heard something about a little weighted glass cylinder that has wax in it. You put the weight on the opposite side of the wax, and drop it in. If the wax is on the bottom, you know it reached 160 at some point and the water is safe to drink.

This method works well in those latitudes for which it was developed. I have tried and tested the method it works as described. Pete

http://www.sodis.ch/

They are/were called or produced by a company called Dydacks (spelling may be way off). We used to use them in our lab, but I believe they are no longer produced. I will take a look to see if there are any left. We have move to a product called an integrator strip. Which looks at temp. (you can get them for various temps.) and time. I do not think for this application they would be a viable option.

On a second note: one reason the solar method of disinfection works well, is not just the increase in temp, but the intensity of UV radiation at the middle latitudes.

Pete

Goatrider:

There is a reusable wax based temperature sensor that you can place in the bottle which resolidifys when removed from the heat. It becomes liquid within its own container at 160 degrees F.

Bountyhunter

bountyhunter,

Yah, that's what I'm thinking of. I won't bother to ask you where to get it, because there's hardly any chance I'll be able to use it in Minnesota.

Brian:

For more heat, you make a collapsible cardboard solar oven painted flat heat resistant black in its chamber with reflective foil faced cardboard sides angled to direct more sunlight into the chamber where the bottle sits.

Bountyhunter

Hi folks,
This is my small contribution to the forum.
I live in Venezuela a so called "3rd world country" and have several hours of traveling, camping and hiking but this is the first time that I heard about this method. What we use to do is the old time classic of boiling the water fro 10 min. and eve some times adding a drop of chlorine solution, same used to whiten clothes, per each litter of water.
Even thought I have to recognize that killing bacteria through UV radiation makes sense, I used all the time to kill odors in the cloth wile I'm in the wilderness.
Hope this helps

UV rays do come in handy. Reading a survival book by Barry Davies I came accross a paragraph stating that if you cannot wash your clothes hang em out in the sun. Kills all the bacteria in them.The trick came in handy while I sailing for 2 weeks, bathing all my rags on the deck during an afternooon sun.

There is always another method to do something. I think this method can be listed with firemaking with an ice lens. It works, but why bother if you walked out the door with duct tape holding your grey cells in place? The perjorative term "3rd World" is equally unrealistic. I can go to some of our indian reservations, appalachia, and freeway underpasses in Los Angeles where Americans live in abject despair. I only live in one world, and it doesn't come with numbers. <img src="/images/graemlins/mad.gif" alt="" />

I have in the past made double chambered solar stills with three clear plastic bottles - 2 2 litre, 1 1 litre/20oz, duct tape and rope. It is based on the bottle compost design.

The tricky part is cutting the 2 litres to be able to put the 1 litre in and taping it up again. You cut the top off of both of the big bottles(about where you see the curve in starting for the top cone) and throw one of them away. Excuse me, recycle it! <img src="/images/graemlins/smile.gif" alt="" /> Turn the remaining top over so that the cone is pointed down into the bottle. Make sure it will fit without falling in. take it back out again. Measure the bottom of the smaller bottle and cut the very top off of the cone about 1/4 inch smaller than the small bottle. Cut 'tabs' and force the small bottle into it with the cone facing down. To make it easier for condensation to get to the bottom bottle, you may want to make holes in the cone, too or cut one or two of the tabs completely off.

Put the 1 liter in the cone(careful!) and put the other bottle bottom over top ofit. Tape up.

Oh, I guess I should mention one minor thing to do before taping it up - You place water in the small bottle. 1/2 full is good, more and it can tip over and spill. Things that can make it better include twigs or cooking skewers inside to keep things propped up, black paper or paint for the top bottle and a good brick wall or big rock for thermal mass.

The rope is to hang the bottle contraption in a tree or from the eves of a house.

I was able to capture about 4 oz of 'distilled' water in a 36 hour period from about 8 oz of crappy water put into the small bottle. Not a great method, and not a great producer, but good to put in a camp when you know you are going to come back in a few days.

Just a thought brought on by the mentioned solar reflector... (my thighs in summer...)

Rena

Gene,

I think I need a picture.

thats a lot of work ... might be easier to build a microwave oven with my multi tool and just nuke some water to a roaring boil <img src="/images/graemlins/smile.gif" alt="" />

That makes a lot of sense and also explains why it is not commonly used (at least not in the states).

I will have to make another one up to get some pics. It is an 'as needed' unit, after all.

Rena
SurvivalGene(.com)

I'd really like to see a pic too. <img src="/images/graemlins/grin.gif" alt="" />

Some links to "practices" for development countries
http://solarcooking.org/
http://solarcooking.org/metcalf.htm
http://solarcooking.org/soda-bottle-pasteurizer.htm

Other projects
http://www.cdc.gov/safewater/
http://ceemeng.mit.edu/~water/

Ceramic water filters
http://ceemeng.mit.edu/~water/ceramic_tech.htm
http://www.potpaz.org/pfpfilters.htm