BushProof Biosand Filter

BushProof Biosand filters work according to the principles of a general BioSand Filter (BSF) whereby layers of sand and gravel are housed in a concrete container. The water level is maintained above the sand layer by setting the height of the outlet pipe. This shallow water layer allows a bioactive layer to grow on top of the sand, which contributes to the reduction of disease-causing organisms. A diffuser plate with holes in it is placed on the top of the sand layer to prevent disruption of the biolayer when water is added to the system. To use the BSF, users pour water into the BSF, and collect finished water out of the outlet pipe into a bucket.

The BushProof Biosand Filters relies on intermittently operated BSF technology. In this design, the drain pipe is raised 1-8 cm above the sand level, which ensures that the water level is just above the sand. Even when water is not continually added to the filter, oxygen can still permeate into the water to reach the bioactive layer by diffusion across this shallow layer of standing water.

When the flow rate becomes unacceptably low, the filter can be cleaned by removing accumulated dirt from the top few centimeters of sand. There are several ways to do this, but all disturb the biological layer which results in less effective filtration for some time. Some methods are less disruptive than others.

BushProof-trained artisans provide technical support, and an instruction booklet can be accessed online.

About 4 years according to research conducted by Medair, Kenya

Safe Household Drinking Water via Biosand Filtration Pilot Project Evaluation and Feasibility Study of a Biosand Pitcher Filter

Water, advocacy, sanitation and hygiene: Lessons learnt from Tearfund’s global water, advocacy, sanitation and hygiene programme 2007–2012. Written by Murray Burt and Bilha Joy Keiru.

Concrete filters can be heavy and difficult to move and transport.