Water filters can be made on-site using local materials such as grass, charcoal (e.g. from burned firewood), and sand. These filters have been used by soldiers and outdoor enthusiasts.[2] Due to their low cost they can be made and used by anyone, including the poor, who often do not have access to safe drinking water. Regrettably such filters do little if anything to mitigate against pathogens and other harmful constituents and can give a false sense of security that the water so produced is potable.
Jan
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