CHALLENGE:  Some simple and affordable water treatments don't have high efficiency rates and/or cannot supply enough water to provide washing, drinking, and cooking for an entire household.

ASD SOLUTION:  The BioSand filter (BSF) is a household water treatment, designed by David Manz, works in the same way as traditional slow sand water filters, which have been used for centuries. The difference is that the BioSand filter is smaller, and water does not need to flow through it all the time. The filter can be built anywhere in the world because it is built using materials that are available. It is simply a concrete container, with layers of sand and gravel inside it. The sand and gravel remove dirt, bacteria, viruses and parasites and other impurities from the water.