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Developed for use in Bangladesh, the cloth filter is a simple and cost-effective appropriate technology method for reducing the contamination of drinking water. Water collected in this way has a greatly reduced pathogen count - though it will not necessarily be perfectly safe, it is an improvement for poor people with limited options.
Method
The method used in Bangladesh is as follows: an old sari is folded to make four or eight layers. The folded cloth is wrapped over the mouth of the container used to collect surface water. It is usually sufficient to rinse the cloth and dry it in the sun for a couple of hours. In the monsoon seasons, it may be advisable to use a cheap disinfectant to decontaminate the material.
The preferred cloth is used cotton sari cloth. Other types of clean, used cloth can be used with some effect, though the effectiveness will vary significantly. Used cloth is more effective than new cloth, as the repeated washing reduces the space between the fibres *.
Effectiveness
While the cloth filter is considered by some water professionals to provide inadequate purification on its own *, it has been demonstrated to greatly reduce cholera infections in poor villages where disinfectants and fuel for boiling are difficult to get.
The cloth is effective because most pathogens are attached to particles and plankton within the water. By passing the water through an effective filter, most cholera bacteria and other pathogens are removed.
In sub-Saharan Africa where guinea worm dracunculiasis infections are endemic, infection is prevented by use of the cloth to filter out organisms called copepods that host the parasite.
Background
The cloth filter was developed by Rita Colwell and Anwar Huq from the University of Maryland Biotechnology Institute.
External links
"Cloth filter"