Clay pot filter

Clay pot filter

The clay pot filter purifies water by passing it through the pores of a ceramic which has been fired in an open dung fire. These filters, intended to be affordable for developing countries, were developed by an Australian materials scientist and potter, Tony Flynn.



These filters are made from a suitable clay mixed with a fine-grained organic waste material such as coffee grounds, tea leaves or rice hulls. Coffee grounds have been found to give the best results. The filter is made in the shape of a cup, then fired without a kiln, using cow manure and a handful of grass and leaves. The organic matter is burnt away, leaving only silica remnant and tiny holes in the filter. As water passes through the tiny holes, it is purified. Water passing through initially tastes soil or is alkaline[1]. The taste of water improves with time.


The filter has been found to remove 96.4 to 99.7% of E. coli bacteria. It does not remove viruses.


The filter was invented as a result of a World Vision project in Manatuto, East Timor. The local clay was found to be too fine for water filters, but this was solved by adding organic matter.

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