The following  are links for the Potters for Peace project  http://pottersforpeace.org/?page_id=9  --which teach the process for making clay pots that not only filter water, but purify the water using colloidal silver which
can be made on site, using any silver coin (which have, but not with
me--it is in the US yet could possibly be obtained locally)

I
have not been trained in this process, yet I'd love to support how one
of the potters collective might be able to tap into this process.  The water that is filtered in this process, can be any contaminated water,
which then becomes totally healthy for human consumption.  The process
has been taught to many people, including a village in the depths of
the Amazon where only the locals visit--the process has illuminated the
death rate for children who become ill from drinking the water from the local rivers.

I
would think that one of the women's collectives that make pottery,
could learn the process, and then sell the pots locally to help
eliminate the need to purchase bottled purified water to
people living both in the villages and also here in Oaxaca--greatly
helping with the economies of the villagers, but also reducing the cost
of water to people living in town here in Oaxaca.

Here is another link to check out:  http://other90.cooperhewitt.org/Design/ceramic-water-filter

this
is information on how people can hand drillling wells which might also
be a way for communities to inexpensively gain access to local ground water.

Youtube videos:
http://www.youtube.com/watch?v=pvHtqsUIoDs and
http://www.thewaterchannel.tv/index.php?option=com_hwdvideoshare&task=viewvideo&Itemid=53&video_id=511
which shows many more links on the subject about water: 

Additionally,
here is information about rocket stove designs,which is a very
efficient way to produce intense heat for heating interior spaces,
cooking, and also can be used in building a kiln, which could be useful
for firing pottery, such as making the water filters. 
the rocket stove design, uses significantly less wood to produce which
reduces the issues related to deforestation --there are a number of
ways to build them, but here is the website for a few of the resources:

rocket stove organ. website:  http://www.rocketstove.org/

the Rocket stove book:  http://www.rocketstoves.com/

youtube basics of design:  http://www.youtube.com/watch?v=9uh2VExcdbY&feature=related
you can also, do searches on youtube for rocket stoves and you will get many more videos on the subject.

Have
fun with learning about these great resources.  I have more info about
these and other sustainable designs which I can share with you if you
like.

Blessings
-- 
Aome St. LaurenceCertified Permaculture Consultant, Designer, Educator
Keep up to date with my adventures on Aome's Journey blog