nothing" Background The cloth filter has been studied and reported on by Rita Colwell and Anwar Huq from the University of Maryland Biotechnology Institute, together with other researchers from the United States and Bangladesh. They report that: "It is common practice in villages in Bangladesh to use cloth, frequently a flat, unfolded piece of an old sari, to filter home-prepared drinks". The researchers studied the application of this technique to drinking water, with folded cloth. They studied the pore size of the cloth, the effect of folding the cloth on the effective pore size, the ability of the cloth to remove particles and plankton, as well as the effect on rates of cholera when used in a Bangladesh village. See also Filtration References External links Safe Saris - Bangladesh NSF Director Colwell Fights Spread of Cholera with Saris Sari filter stops cholera, with photo. ICDDR,B website. Photo showing woman using sari to filter drinking water - Source: Dr. Rita Colwell Filters Water Appropriate technology Survival skills