Water filter

A slow sand filter, or Biosand filter, is a type of water filter that uses sand, stones, and a layer of good bacteria to filter contaminated water. A Biosand filter can be up to 99% effective at removing organic contaminants, including bacteria and viruses.

Many designs have been used, ranging from large concrete cisterns to small individual sized plastic containers. We have been working on making a small sized filter that can supply enough drinking water for a household in Malawi. After the results of our initial water tests, we feel compelled to improve the situation.


After constructing the water tank, we filled it with stones and sand as recommended but found the sand too muddy. We are looking for an alternative to the sand we found. One idea is to dig out sand by river bends. Hopefully, we'll find what we are looking for.