Clay, sawdust and a plastic ...

Clay, sawdust and a plastic bucket can make a water filter that catches dirt and disease-causing microbes. In the classic design, mix clay with a combustible material like sawdust or rice husks, give it a flower pot shape and fire it in a kiln. The sawdust or rice husks burn away, leaving tiny pores in the ceramic through which water filters. Organizations around the world have been using this kind of ceramic filter to reduce disease in impoverished communities for years.