Clay pot water filters


I have been busy this week working with the local potters.  There is a collective of women potters whom live in the same area near the Lumemo River, Ifakara.  They collect clay from the river and hand craft items for sale.  The ladies are very skilled at manufacturing different shapes and sizes.  They use wood, charcoal and rice husks to fire the pottery insitu on the ground.  Their biggest seller is a jiko,  a small cooker powered by charcoal.  They also produce pots for grain and water storage.  

Through research I found out about ceramic water filters.  These simple and cheap water filtration devices remove between 95-99.9% bacteria, (but not viruses).  The technology was pioneered by the NGO Potters without Borders.  These filter pots have been very successful and widely accepted in Asia.  There is a large factory in Cambodia now producing over 3000 per month!


The pottery situation here is a little different.  It is very primative, no machinery or kilns.  Pottery is done at the home, not in a factory.

On first approach the women were very sceptical and laughing a lot at my idea for them to make a pot that allows water to pass.  It was very difficult for them to comprehend what we wanted to achieve!  After much discussion, patient translation, pictures and demonstrating the women were happy to try and build some trial pots.

How it works: Well the novel idea is to mix ground rice husks into the clay mix.  When the pots are fired the husks are burnt out of the clay, leaving very small voids in the clay, creating a flow path, that allows water to pass yet traps solids to a microscopic level!  

It sounds doable in theory.  Now we practice!  The women will be doing an experiment, testing 4 different clay/rice husk mix ratios.  The biggest challenge will be the firing process.  Im not sure if the heat will be sufficient to burn out the husks - the kiln temperature in the Cambodian factory is a whopping 865 degress C.  Keeping positive, assuming the process works we will test the flowrates through the pots and so some lab tests on bacteria removal efficiency.

Oh btw, the filter pots will be shaped to fit inside a standard 20L bucket.  The 20L bucket is the standard water collecting tool in Tanzania- and basically every household has one.  The beauty (in theory) of the the ceramic pot filter is that it can fit on top of any bucket and be used to filter water.  It can be taken to the field when people are working and living on their "shamba" - each family has a plot of farmland outside of the towns/villages to grow crops such as rice/maize. Water quality is a big issue in the shamba areas.

The cost negotiated for the experiment pots is 4000TSH per pot, about AUS$5.  Believe it or not, that is quite expensive - but the women were very apprehensive about the additional work requried to make these filters compared to normal pots.  Ultimatley if it works and becomes a business it is they will have to set a price that the market will accept.  I would assume if it works the actual market price will be around 1000-2000 TSH per filter!

The picture is of a local potter woman with the first protype Ifakara water pot filter!