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Alessandro Jones
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Good morning!
I am an Italian person interested in drinking water technologies, even if I am not an expert.
I found a topic in this forum about bio sand filters and SODIS.
I didn't read it carefully yet, but I'd like to know if you are interested in drinking water for poor countries.
I'd like to create an informal group of people interested in drinking water:
SODIS, artificial UV radiation with lamps, sand filters...
I don't know if this is off- topic for this forum. Is there anyone interested in this?
Thank you!

Alessandro
 
John Polk
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Safe drinking water is one of the most often ignored problems in the world today.
It is not just the poor countries at risk.  In many well developed countries, the infrastructure for our drinking water supplies is well over 100 years old, and beginning to fail.  Many large cities are spending millions of dollars every year just to keep the systems operating.

Rich or poor, this is an issue that needs worldwide attention if an essential element of human survival is going to be provided to all.
 
Alessandro Jones
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What could we do? Very often a PET bottle can save many and many people. A sand filter and a tin foil could help improving the effect.
And this is free.
 
                        
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These people have done something.

http://eartheasy.com/lifestraw

This version is a personal one worn around the neck they also have a larger one.
The company has distributed many of them in Africa..I believe that a portion of every sale is put into the effort to send more.
 
Alessandro Jones
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Thank you!
If you want we could share many other informations, if one of us would find something interesting.
The filter you are speaking about is not free. For me it is interesting, but if I would tell you about a product I wouldn't tell about something to buy, but only about free devices, because I don't want to compromise the volunteering aim ( I would be considered a seller, and I would not be believed. ). But from you I have no problem if you tell about a product to buy, however that product should be bought by generous givers.
Sometimes a product to buy is the best thing, and the filter you found is very good, but I would consider it as the last possibility.
I thought that a filter could have 2 effects: 1 remove the water turbidity 2 remove microorganisms.
For the SODIS method the first effect is sufficient, however a filter with the second effect could replace completely the SODIS method.
There is also another thing: ultraviolet lamps can kill many microorganisms. I started this research because I read about ultraviolet lamps, but one method for water disinfection based on UV lamps is patented, and maybe many others. I don't know if a single UV lamp is patented.
However, I didn't find the answer and I am still looking for it, but a filter, a PET bottle and a tin foil could do a lot.
 
ronie dee
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Doesn't the sun put out UV rays and kill microbes with just a little heat.. As for turbidity, doesn't settling and sand filtration get rid of most of it?
 
Alessandro Jones
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Ronie, the sun is not only a good idea, but a solution.
The sun is not as good as an UV lamp, but it could be the solution in many and many situations.
If a tin foil ( for a parabolic collector ) and a sand filter are available, the sun could be the solution in many other situations.
If any other devices ( in addition to 1 the parabolic collector and 2 the filter ) are available, the sun could be the solution in many other situations ( Ronie, you added the settling, number 3 ).
I said that the sun is not as good as an UV lamp, because some microorganisms can be killed only with a high UV radiation.
The sun ( the SODIS method ) is a solution, it is free, it is no patented.
"some microorganisms can be killed only with a high UV radiation", this is a problem, but in that situations ( only a little part ) there could be other solutions: other disinfection methods ( chlorine, ozone... ), prevention, if anything else is better some people could decide to pay for a patented device, etc.
I explain this: "if anything else is better some people could decide to pay for a patented device":
I said in the previous post that a disinfection system based on UV rays is patented.
I was speaking about a specific real situation: a laboratory patented a disinfection system based on UV lamps. But some NGO work with it, pay a little and use that device.
This is what I think:
as I said in the previous posts, I don't want to speak about patented products,
I am a bit sad because that method is patented ( even if some NGO use it and think that it worth it ).
I am a bit worried because maybe the other methods based on UV lamps could be patented now or in the future.
I am a bit worried because a single UV lamp maybe is patented ( but maybe it is not, and I'd like to know it ).
I am happy because, as Ronie said, the sun is a good idea.
It is not "the" solution, because an UV lamp is better, but it is "a" solution in many situations. And maybe there are other solutions for the situations where the sun ( SODIS ) is not enough.
And it can work better with a parabolic collector, a sand filter and the settling.
This is free.
How many devices are free and could give drinking water?
 
ronie dee
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200 degree simple solar oven do you any good?

4601617298_55b9b40cfa_b.jpg
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4601617018_bab22397fe_z.jpg
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Slow sand biofilters do help if only to bring down the turbidity. For those who does not know, turbidity can harbor coliforms which is used in labs to determine potential risks of pathogenic bacterias.
What is the SODIS method? Can you explain it more?
 
Alessandro Jones
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Thanks to everybody!
From Wikipedia:
"... Solar water disinfection, also known as SODIS is a method of disinfecting water using only sunlight and plastic PET bottles. SODIS is a free and effective method for decentralized water treatment, usually applied at the household level and is recommended by the World Health Organization as a viable method for household water treatment and safe storage. ..."
"... is recommended by the World Health Organization... "
If you read the Wikipedia page, there is the paragraph "Cautions". In this paragraph you can see some dangers, for example this: "Leaching of bottle material". Despite the leaching of bottle material, the WHO considers this method safe.
Of course we can discuss about the leaching of bottle material, but there is a thing we can't discuss about: it is free.
Now, starting from the fact that it is free, we can discuss about the leaching of bottle material. WHO says it is safe.
Thanks to everybody!
I am looking for free ideas for water disinfection. If you want to add your ideas I am at your disposal.
I tried to do this before with 2 persons, but without success.
If you want to talk about water disinfection, but also about renewable energy that can help in water disinfection and in many other things ( for example, the tin foil I told about, the parabolic mirror, solar power, wind power... ), we could talk about this by email.
I am interested in anything that could help in volunteering projects.
If you want we could talk about this by email, because I don't want to be inopportune here, or if you want we could talk here, or stop talking.
I am looking for ideas like these of this topic, a sort of personal research that could be useful for people interested in volunteering projects.
You can find useful informations in WHO website, if you indirectly look for: "Water Sanitation and Health (WSH)" in your browser. 
If you are interested in this, I am at your disposal:
1 if you have something to suggest, you can tell me about it by email or here;
2 I have anything else to say;
Thanks to everybody!
 
ronie dee
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They wouldn't have to worry about the plastic leaching toxin into the water with the simple solar oven I have pictured. They could settle the water, then pour through the sand filter and put water in a glass container and place into the solar oven.

Are you mainly looking for a system for a family or a system for a larger unit of people?
 
Alessandro Jones
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Thank you Ronie!
I am looking for every idea that could be useful for volunteering projects.
In particular I am interested in drinking water, water disinfection methods and renewable energy that can help ( for example solar or wind power to produce UV rays ).
1) I am doing a personal research on these devices.
2 A) I am looking for ideas that could be useful in volunteering projects ( I'd like to create an "encyclopedia" ).
2 B) Then, if you want, I am at your disposal if you want to read the constantly updated document.
This is my "project".

If you want I could write the updated document here, but by now it is not necessary: it is a list of the renewable energy forms and it mentions parabolic collectors, the SODIS method, the UV rays method, sand filters, chlorine. OK, I have just told you. I am going to add everything that you wrote in this topic.

I told you that I tried to do this before with 2 persons, but without success.
However I am going on with my personal research. I think that it could be useful.
I don't know what to do, I am simply going on with my personal research.
 
ronie dee
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Well this thread might be a little misplaced, but I think it is very important for everyone to get involved in. Whether the person is off grid and catching their own rainwater, or using a well or pond to collect water to drink. So keep on posting your findings and somehow the world will gain from your works.

I saw an old TV screen in a dumpster Monday and it had a screen that also could be used as a Fresnel lens. I am very sure about the lens being quite capable to sterilize water as the lens caused a fire in the dumpster while i was there. This would require at least 451 degrees F. I think that the Fresnel lens could be much hotter.  Here's a link to someone on youtube boiling water with the Fresnel lens:

http://www.youtube.com/watch?v=e4iU9kbn1wI

And melting a brick:

http://www.youtube.com/watch?NR=1&v=9RUF_g9nrTY

There is enough energy in sunlight to sterilize water - we just need to figure out how to concentrate the light.
 
Alessandro Jones
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Thank you!
As I said, I don't want to be inopportune here, I don't know if this is the right place to talk about this.
If you want we could talk about this by email, my address is volpeegiziana at gmail.com
I am at your disposal if I could do something for you.
Thank you!
 
ronie dee
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Hey Al I think it's OK to continue posting here. The Admin can move this to permaculture if they want.
 
paul wheaton
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I've received emails from folks suggesting that I move this thread, but I think it is in the right spot.  It sounds like we are talking about building something really cheap that will clean water. 

I think it would be good to talk about Art Ludwig's book about "water storage" with a bit of a focus on the parts about how some systems have water that gets cleaner with age. 

I think it would  be good to talk about sand filters.

 
Alessandro Jones
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Ronie,
of course, don't worry.
I'm sorry, this misunderstanding is my fault.
Infact I said before that I wanted to talk by email, on October 31, 2011, 05:23:18 PM.
This is because I wanted only to find a solution, a conclusion to this topic.
So, I didn't write that for you, but because this could be useful for my "project".
Now I am wondering if my "project" could be useful for anyone, and this is the most important thing ( and in your previous post you wrote that it is useful, so you encouraged my "research" ).
OK, I found the conclusion:
1)
I said that "Now I am wondering if my "project" could be useful for anyone", with this topic I understood that it could be useful ( not my "project" in particular, but the ideas it is about and the people interested in these ideas, who do not necessary know the project );
2 A)
I am doing this research because I think that a parabolic collector, the SODIS method, and every device we talked about are exciting ( I love them! );
2 B)
you added your ideas ( I love them too! I didn't know the Fresnel lens, and also every device you talked about is great! ).
So, this is the conclusion:
I love these devices, I am at your disposal if you want to talk about these devices, I don't want to be inopportune here, I don't know if this is the right place to talk about this, if you want we could talk about this by email, my address is volpeegiziana at gmail.com, or if you want we could talk about this here.
The conclusion is this:
I am going on with my personal research, you could add your ideas, then I can write the "constantly updated document" with our ideas ( here or by email ).
If this discussion finished because it could be abandoned and forgotten, I would continue my personal research by myself.
"A conclusion for this conclusion" is that if we all talked about this by email this discussion wouldn't be forgotten, and we could see who are the people interested in this discussion.
Then, if someone was interested in reading the result of the discussion here, I could write it here.
Thank you, Paul! We could write here something about sand filters, and by email we could talk about everything that is not appropriate for this forum.

So, I am going on with this research, if anyone would join you all are invited.

But I think that this discussion could be forgotten, so I don't want to say anything else, consider this message as the last, because if I could do something for you or if this project could be useful to you, I'm here until this discussion will be forgotten, and this depends on you.
So, tell me what could I do for you, let's talk about sand filters here ( or everything else that could be appropriate for this forum ) and if I could do something for you or if this project could be useful to you, I'm here, you could write me by email until this discussion will be forgotten.
Thank you!
 
ronie dee
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Hey Al, Paul is the site owner so he thinks it's OK to continue right here. By putting ideas here, others can read and maybe comment. If anyone manages to get enough information here to clean their water and avoid illness, then it will be a good thing.

I also wondered if you ever heard of drilling or digging beside a pond, lake or stream to get cleaner water? So in this method, you find a sandy spot uphill from the water and dig down a ways beside the water and when you did far enough the hole you dug will fill with water.  This side hole is pre-filtered water that sometimes is clean enough to drink.
 
Alessandro Jones
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Thank you, Ronie!
I heard about that method, I talked about it with a person who has been in Ethiopia and he said that, in this case and in general, it is necessary to see that the place is free from animals that could pollute the water.
Thank you for your information, I will add it in my research.
I began this research for a personal interest, and I am still interested in this, because I found out the parabolic collectors, and some other devices to get drinking water or devices that could be useful.
I am still interested in this research because I love parabolic collectors, for me this is sufficient.
However there are many other devices.
Ronie, you are going on in talking about these devices, I am going on in adding them and, if I found something that could be interesting for you, I would write you about it.
Now I can only say that I love parabolic collectors, and for me this is sufficient.
So, this is the only thing I can give, tell me if I could do something for you.
 
ronie dee
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Yes you must keep all animals and even as many microbes out of the ground filtered water as possible... I think that a box of somekind needs to be placed over the hole.

You can pm me on here if you need to, but I prefer that you place any ideas and photos on this thread and share them with the world.


 
Alessandro Jones
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Also a fence could prevent a contamination.
About the SODIS method there is the possibility to increase the effect with a parabolic collector ( or a generic collector, this is called SOCO-DIS ), and about the "leaching of bottle material", that could be a serious problem, there could be many solutions, you found a solution, it is sufficient that the water doesn't touch the PET plastic, for example the plastic could only cover the water.
However the WHO said that the leaching is below WHO guidelines for drinking water, but this is a very important issue.
As I said before, you could find useful informations in WHO website, if you indirectly look for: "Water Sanitation and Health (WSH)" in your browser. WSH is related to WHO.
The subject of this research:
about WSH, this article can represent the subject of this "research":
http://www.who.int/water_sanitation_health/dwq/wsh0207/en/index4.html
The aim of this research ( only a personal interest ):
in the same article you can read that UV rays are very good, but I said before that these devices based on UV lamps could be patented, so the information given by WHO could be not true, the aim of this research is to find out if a single UV lamp is patented ( but this is only my personal interest ).
I said that my personal interest is to find out if a single UV lamp is patented, but here it could be useful to know for every device if it is patented. ( The SODIS method, with the cautions for the leaching of bottle material, is not patented. )
I'm sorry for the lenght of this message, I wanted to write also the aim of this research that is a personal interest, however everything but this could be useful, and I add something else that could be useful: if you open the link I wrote, you can see the article about "Heat and UV radiation", and on the right you find a list of relared articles ( whose number 5 is the same article ), those articles could be interesting.
 
ronie dee
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AL, What is it you want to do with the water disinfection information? Are you wanting to clean up your water?
 
                                    
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Hi great topic.

I would love to see some pics of designs to build a basic water fitler system. Also what sand should I buy, BPA free containers for sure, do you just pour the water in top and collect the clean at the bottom? Details and the more the better.

I am thinking about collecting rainwater and then filtering. I dont want chemicals. I dont mind the idea of UV light, How does it work with this parabolic dish. I liked the lifestraw idea. 20 bucks for 1000 litres. Not bad. Anyway when I build my green cottages I want to catch and clean my water so this link is very important please dont stop.


 
Alessandro Jones
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Ronie,
it is not for my own use, but a personal interest.
I'd like to know if these devices could be useful for a NGO on the field and what could a person do with his own resources.
This could be useful for someone, for now it is only a personal interest and it could remain a personal interest, but I'd like that this could be useful for someone. Infact for now it is only a personal interest because I didn't found how these informations could be useful.
 
ronie dee
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You see Al, Enviroman has a specific problem to overcome... It could have several answers to resolve the problem.

An interest on your part doesn't give me much to go on. DO you want to educate a specific audience as to what can be in their water?
Do you have a specific town, village or family that has a problem with their water?

You see - planning and getting ideas is great, but getting to a specific problem can have unique answers.

Are you planning to take your solutions on the road to a country or what will you do with these answers to disinfecting water?

I am only an idea man, I won't be going on the road to solve others unique problems - I can only throw ideas out from here..

I have an interest as I have a water problem on my land that I've been working on and also have and interest that people near and far are educated of the 'invisible' microbes in there water as well as possible chemical contaminates.
 
Alessandro Jones
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Maybe there is a misunderstanding, or maybe there is not.
"personal interest" could mean:
1 personal benefit
2 something that "I" love
I don't know if this is a misunderstanding, but if it was so, I specify that I talk about something that I love, the second possibility.
There is an important thing to observe: you asked me if I want "to educate a specific audience", I'd like to share these informations, but if you look carefully this topic, you will see that I'm not here to "give" informations, but to "look for" informations, infact you spent a bit of your time for this, but I said that the only thing I can say is that I love parabolic collectors.
I think that this could be useful for volunteering projects, but maybe it is not useful.
So I don't know if this is a good idea.
However I am at your disposal if I could do something for you.
So, I am interested in volunteering projects, but I am at your disposal if I could do something for you.

Enviroman,
I don't know any information about sand filters, but this is the article I found in this forum, and it is for this article that I began writing in this forum.
http://www.permies.com/permaculture-forums/6576_0/permaculture/bio-sand-filter-and-sodis-solar-disinfection
 
ronie dee
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What kind of volunteering projects are you talking about Al?  Would you be personally going to places being the volunteer that helped getting clean water to the people? Or would you be gathering information so you could give it to others that are volunteering to get the clean water to the people or some other volunteer work? The reason I was pushing for a target audience is because there would be different information to give to a child, about how to avoid water born illness, than information that would be given to a parent or other adult.

Some education projects could be directed at those who were dumping raw sewage upstream from some other folks water source.


I understand what personal interest means. I have a personal interest to gather info to get clean water to my farm land. I also have an interest to help educate people to get clean water for their own use. I think that everyone has a right to have water that won't make them sick.

I have always believed that I will have to build a solar still to clean up the water on my land and I am still thinking that i must have a solar still because the other methods, that we have discussed on here, won't help with the chemicals that the farmer uphill uses on his corn and beans.
 
Alessandro Jones
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Ok, I think I am lucky because I had many ( too many ) possibilities to talk about what I am interested in, but you are right, because I still didn't answer to this question, even if the answer could be hidden in my questions and in the fact that I consider useful your answers.
The answer could be this:
1 A) as I wrote before I don't know if these informations could be useful for volunteer projects or not, and this is an important issue;
1 B) at the same time this could be useful for you or not, and for other people or not;
2 I said that I am looking for informations, but, at the same time, I'd like to share the informations I would find;
3 "I am at your disposal", this is an important aspect, because I am interested in these informations and for this I am looking for people interested in the same thing, and to whom this could be useful ( but for now you helped me and I didn't help you ). I said that I am not an expert, I am looking for people who could use these devices, they could be volunteers, and I am interested in volunteer projects, and I am interested in volunteer more than in this research.
4 As I said, I am more interested in volunteer projects than in this research, and I think that voluntary works are completely different from this, a volunteer is "on the field", and I am not doing this, but I could answer to your question saying that I think that this ( to be a volunteer "on the field" ) is the most important thing to do.
Now I am doing a personal research that is not volunteer, I said that I don't know if it could be useful, it is only a personal interest, less important than volunteer projects, but of course I hope that this could be useful. This is another important aspect, infact this "research" will always have the second place, and I have to remember this.
 
ronie dee
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I followed the link to the other permie site and there is something called a biosand filter that looks promising.
This is a link to the description of how it works and a pic of the biosand filter:

http://www.friendlywaterfortheworld.com/page25.html

This is a pic by CAWST and it was made open source by them so it isn't copy right protected:
The top layer in the filter has an area with 'good' microbes that kill the 'bad' microbes that cause illness.

After the water is filtered they still recommend heating the water with the SODIS method or using chemical disinfection.
Biosand_filter_desc.jpg
[Thumbnail for Biosand_filter_desc.jpg]
 
ronie dee
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Enviroman wrote:
Hi great topic.

I would love to see some pics of designs to build a basic water fitler system. Also what sand should I buy, BPA free containers for sure, do you just pour the water in top and collect the clean at the bottom? Details and the more the better.

I am thinking about collecting rainwater and then filtering. I dont want chemicals. I dont mind the idea of UV light, How does it work with this parabolic dish. I liked the lifestraw idea. 20 bucks for 1000 litres. Not bad. Anyway when I build my green cottages I want to catch and clean my water so this link is very important please dont stop.





When I was a kid we collected rainwater for everything and we could drink it right out of the cistern. The water got stale sitting in the cistern and didn't taste good. Now days, with all the industrial pollution, I'm guessing that you would even need to get your rainwater tested before drinking it.

To keep the rain water from going stale it needs to be circulated to keep the air in the water. If the water sits still it goes stale - plants don't mind and it's still good for washing - but it doesn't taste good with the air gone out of the water.
 
Shawn Bell
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Ronie,

Thanks for that link, at the CAWST site there is a downloadable pdf file that shows how to build them.
 
ronie dee
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Hey Shawn I was looking for that pdf while I was there - can you put a link to it here? I read that it costs about $50 and lasts for 30 years. The up front 50 may seem steep, but 30 years later it is barely over a dollar a year for water.
 
                                    
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Excellent, Thats just what I wanted. The picture above and the link, I checked it out, and it is on my list of projects to do. It might be a while as I am knee deep in clay dirt for my building experiments but I know I will build one for sure next year. In fact  I am looking around for the parts already.

Cheers guys, this link gets my thumbs up.

Enviroman
 
Erica Wisner
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My husband and I are interested in clean-water technologies for coastal disaster relief.  Using on-site materials when possible.  I would love to hear about other methods.

The sand filter is a great basic technology, thanks for sharing the diagram.

The PET bottle-in-the-sun method (SOL-whatsis) is also very useful for equatorial regions.  There are worse things than water has been sterilized in warm, food-grade plastic; yuppies pay a lot for PET-contaminated water.  And the solar process does seem to kill off most pathogens in clear water.

Narrowing down the discussion:
Alessandro, there are a LOT of ways to filter or sterilize water.  All are interesting, and some are useful.  But if you want GOOD ideas, you need to know what situation they should be good FOR.  (purpose).  In a specific situation, one method may be better than another.  

These forums mostly involve two kinds of situations:
1) appropriate technology for home use, such as farms and urban eco-homesteads; and
2) appropriate technology for low-impact or primitive use, such as for the third world, outdoor survival, or disaster relief.
We are happy to think about other situations whenever someone describes them.

For coastal disaster relief, we have been looking for portable methods, and methods that can be copied using local materials.  We have lived and camped in 'primitive' wilderness areas in North America and elsewhere.  We carry our own water purification, and/or use systems set up and maintained by locals, such as sand filters and wells.  So these are the situations I think about for 'free' or 'affordable' water purification.

Regarding your question about UV patents: I don't know what variations of UV technology are patented.  In the US or elsewhere.  But the patent should not stop you from re-inventing something for personal use.  It is rare to have problems with patent infringement unless a person is publishing or selling patented technology.  

* * *
Regarding "Free" technologies:

Clean water is rarely free.  There is always a cost in time, money, or materials.  
The question is, how clean do you want the water, and what are your resources?

Charcoal, sand, PET bottles, terra-cotta, concrete: available in most places, but not free everywhere.

How bad is the water to begin with?  Salt, fertilizer, petroleum; giardia, cholera, typhoid; rain or drought; donkey poop or bird guano; or what? Sometimes filtration is enough, other times distillation or boiling won't even remove industrial wastes.

  In places where wealthy nations have sponsored a new well for 'free' water access, there have been problems with finding replacement parts when the seals or pumps wear out, or accessing the parts for maintenance with limited tools.
 Charging a small amount for each gallon of water (like 3 cents) can be enough to allow the village to replace those parts, or even send someone to school to learn how to maintain the well. Likewise, when people pay for a personal water filter, such as a ceramic or sand filter, they are often more likely to maintain it than if it was given for free.  Working or paying for something, in many cultures, indicates that it has value.  Free things may not be valued.

 Time is also valuable.  If a person is too poor to buy clean water, or to maintain a clean well, they are likely to be busy with the work of survival.  Not likely to have spare time for education, research, or extra chores.  It is important to consider what locals value enough to spend time on, and what options they would accept.  Children's health is often a starting point for discussing community needs.

 So if you want 'free' methods, are you specifically looking for short-term solutions that will be used and discarded by refugees or campers?  
 Or are you looking for a method that can be reproduced locally, using local materials, without imported parts?  Local methods often cost more, in time and effort, than purchased methods.  But they can be more resilient when economies shift.

I suggest considering 'nearly free' or 'affordable' options as well as 'free' ones.

* * *
Water sources and purification methods:

Salt water can be purified by solar distillation, or reverse-osmosis filtration, among other methods.  These may also work on river water contaminated by farm pollution, or some kinds of industrial pollution.

Fresh water:
Distilled:
Rainwater and distilled water are basically pure already.  The trick is collecting them without also collecting bird poop, mold, or other contaminants.  Several rural friends drink local rainwater without any treatment.  They gather it from a clean roof in large bottles, which are replaced every day or two.  The roof is cleaned and inspected a few times per season.  As long as the collection area stays clean, this works OK.  They are still alert for sickness and drink a lot of boiled tea, but use rainwater for dishes, teeth cleaning, and in small amounts for drinking.  
 In low-rainfall areas, solar distillation methods can collect water from earth or plant matter, and this distilled water can be used (when fresh) without further treatment.
 Most well water can be used with basic filtration, as long as the well is protected from livestock and sewage leaks.
 Ice and snow are mostly pure; even sea-ice will (over time) purify itself from the top down.  Freezing the water and thawing it again kills many pathogens, but takes a lot of energy.  Some areas have frozen water available when fresh water is scarce.

Stagnant water:
 Water that is saved in a cistern is stagnant (standing still) and likely to breed contamination.  No matter how clean, stagnant water should not be trusted.  Boil or disinfect before drinking.  I have seen clean (previously chlorinated, filtered) tap water, in a clean glass, in the fridge, grow fungal snowballs and black mold colonies, when left long enough.

Running (Aerated) water is generally cleaner than stagnant water.  Aeration can help keep water fresh longer.  In the wild, running streams are cleaner than stagnant lakes.  
But any open water source can be contaminated by unseen problems upstream (a dead animal, fecal matter from ignorant campers or livestock, sewage from upstream villages, fertilizer and pesticide runoff, etc).  

Many places in the world collect water directly from rivers or open water sources; ANY filtration method is an improvement.  Even filtering through 4 layers of an old cotton sari will remove a large proportion of cholera and other large parasites.  Water will not be 'clean,' but 'cleaner' than it was. (Research over 10 years old, for use in India.)

Filtration:
For water filtration in special situations, many commercial tools are available to make water safe.  Chemical, charcoal, ceramic, and reverse-osmosis filters are available for home systems and in bottles for camping.  These cost different amounts, and some last longer while others need frequent replacement.
  Filters that stay damp collect biological activity.  Sand filters use this to improve filtration; charcoal and commercial filters may become less effective once biological activity begins.  Bioremediation can also be used to help decontaminate local groundwater and creeks; paul stamets lists mushrooms that concentrate or break down things like petroleum and heavy metals.

Boiling water is an ancient method of sterilization.  Tea-drinking is a healthy part of many cultures, and sometimes becomes a sacred or high-culture art form: it ritualizes the boiling of water for drinking, protecting its practitioners from dehydration and water-borne diseases.  Tea-stoves and solar cookers can boil water with minimal or no fuel.

If I am camping or building a primitive shelter on unimproved land, I look for running water from a spring, and then use the easiest available method to sterilize, such as boiling.  (Where I live, there is plenty of water, and plenty of wood.) 
I prefer boiling over adding iodine or chlorine; water can almost always be boiled using locally available materials.  If I have to use tablets, iodine might be more nutritious than chlorine in dry inland areas.  I personally prefer boiling to PET sterilization.  Plus, I like tea.

Adding alcohol can also inhibit bacterial growth.  I don't know what concentration is considered sterile.  We used 4% alcohol to preserve bio-extracts in a laboratory setting.  4% is about the same concentration as the European 'small beer' that was served to women and children in the Middle Ages.  

Tuscans still drink wine and water together, mixed to each person's desired concentration at the table, and this is not considered primitive (except possibly by the French).

Please let me know of any other methods you find interesting or useful.

Yours,
Erica Wisner
www.ErnieAndErica.info
 
Alessandro Jones
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Thank you for your answers.
Erica, I agree with you, infact I am looking for the best ideas, without considering the price, however personally I like to begin from cheap devices. That devices are 'nearly free' not only because even a simple PET bottle has a little cost, but also because sometimes if you pay a little for a patent, or if you have to buy the materials, it is worth it.
About chlorination, some chlorine compounds or some compounds that chlorination produces could be carcinogenic.
I don't know well this aspect, but maybe we could talk also about this.
Infact, as for the SODIS method, this method could be dangerous. About the SODIS method the WHO says that it is dangerous but far below WHO guidelines for drinking water. However these two methods could be dangerous for our health. I don't want to say that these methods are safe, however I still have many hopes for the SODIS.
Shawn Bell, I didn't find the pdf file, I'll look for it better, but if someone could post the link, as Ronie suggested, it could be useful. Could you post it, please?
Ronie, I knew the solar still idea, I think that it could require a lot of solar power, I hope it could be useful for you, for volunteer projects it is very good.
 
docooley tang
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I'm in the process of putting together a Biosand Filter. Most of the info you can find online shows Biosand filters made from concrete.. not so sustainable, and harder to make. A 55 gallon food grade plastic drum works just fine, and can be found or purchased for pretty cheap. Along with the drum, some scrap PVC piping and a few different PVC attachments is basically all you need, beside the gravel and sand. I'll post some pictures of my Biosand filter soon, it's not complete yet, but the meat of it is done. I think its an incredible way to filter water, super cheap, easy to make and as simple as it can get. Cheers.
 
Jay McReed
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The solution given below is not for portable or instant uses. But it's the best solution I've seen for a home or other permanent installation...

Advantages:
- Low cost
- Low tech - you can build it yourself
- Low maintenance
- No consumables like filters to keep replacing
- Tested more than 10 years in the real world
- The main concern I've read is lack of minerals in the water, but you can get easily get the minerals your body needs from other sources, example eating vegetables
- In temperate winters the same method can be powered by fuel

Here are the links:
http://www.epsea.org/stills.html
Presentation with some water quality analysis and cost/gallon: http://www.epsea.org/borderpact.pdf
10-year test results: http://solar.nmsu.edu/publications/1437ISESpaper05.pdf
 
Todd Parr
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Location: Wisconsin, zone 4
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Jay McReed wrote:The solution given below is not for portable or instant uses. But it's the best solution I've seen for a home or other permanent installation...

Advantages:
- Low cost
- Low tech - you can build it yourself
- Low maintenance
- No consumables like filters to keep replacing
- Tested more than 10 years in the real world
- The main concern I've read is lack of minerals in the water, but you can get easily get the minerals your body needs from other sources, example eating vegetables
- In temperate winters the same method can be powered by fuel

Here are the links:
http://www.epsea.org/stills.html
Presentation with some water quality analysis and cost/gallon: http://www.epsea.org/borderpact.pdf
10-year test results: http://solar.nmsu.edu/publications/1437ISESpaper05.pdf


Thank you. That is exactly what I have been looking for.
 
cicily ray
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Drinking water is important to drink for the live life.Drinking water is important to remove dust from body.We must drink purify water.Daily morning drink water is important to lose weight easily.
 
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