Subject: Simple designs for potable water treatment in third world disaster
Date: Mon, 04 Dec 2000
From: Art Ludwig <Oasis Design>
To: Joe Morgan <morganh©fwbnet.com>
Joe Morgan inquires regarding water supplies and greywater for third world
countries, for both dry (Africa) and wet (South America). He is interested in
surface water, rainwater harvesting, and greywater treatment and reuse:
> Looking for information on low cost, easy to implement systems for
> disaster/emergency situations in third world countries...
> I hope you can help me, I may not be able to arrange for any immediate/short
> term purchase of any of your products but your knowledge could be very helpful...
> My dilemma is this:
> Most systems that the UN/military base their systems are heavy in chemical
> use and MICRO filters... I am looking for information on simple, easy to implement
> systems that can be built from local materials if need be - to take stave off water
> borne disease epidemics... However, in the long term your products may be helpful,
> as the populations become more dependent on "clean" water, and rebuild their
> community infrastructure , your products may very well become in demand......
> Bottom Line: Most "emergency handbooks" and military Preventative Medicine
> manuals have a western bias to the standard/methods used to purify water...I have
> read that very simple measures... straining though sand / or even the cloth
> of a "sari" can have significant impact in bringing waterborne diseases epidemics
> at least to "manageable" levels....
> What are the facts? Do you have a range of workable designs?
> (from a two liter bottle filled with sand/gravel of X size- if it works) to community
> cisterns/filtration systems....)
> Some of the other info you have - from solar to waste / composting systems are
> also very interesting and of great value to our efforts to get some "real" info and
> the development of some "pilot" teaching projects...
> JL Morgan
> LTC, 350th Civil Affairs
Honest answer: I don't know. However, see http://oasisdesign.net/consult/egmauruatatest.htm#m35 for some relevant
testing I did for sand filtration.
I don't know about sari filtration but I'd be dubious. With a sand filter, it
is bacteria colonizing the surface which do the actual treatment, and the
filter is not nearly as effective until they are established, which takes
several days, but which time the sari would be starting to rot.
I bet that an effective sand filter could be made, however I expect that some
trial and error in the field would be required to establish practices and
protocols which were truly effective in third world disaster conditions.
I'd start with something like two half-sand filled 1 m3 concrete boxes next
to a community well. You pump and the water goes directly into the hermetically
sealed box, then the water comes out the bottom, rises to a bit over the level
of the sand, and goes out a tap. Some authorities say sand filters have
to have continuous flow, others don'tsee
Perhaps you could post my reply to the greenbuilding list (I'm not signed up at
the moment) and others will have comments.
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