VHP started implementing biosand water filters (BSF) in 2006 as another method to increase access to clean water. We began this project with the idea that these smaller and lower cost filters would be beneficial for private usage. To start this project VHP funded Paul Kimera, a Ugandan engineer, to attend a Rotary conference in Michigan to learn the filter technology for BSF. The filters work by moving water through a series of layers of organic matter which removes water borne diseases as well as silt, sand and organic matter. One major distinction between the rainwater collection tanks and BioSand water filters is that the tanks mainly address the issue of quantity of water and the filters address quality of water. Similar to the tank project, Technology 4 Tomorrow (T4T) is in charge of the technical aspect, CoBIN for promoting the filters, selecting filter recipients, and educating the public, and VHP for raising the funds necessary for the project.
As of February 2011, VHP has 39 filters: 18 installed, 11 at the CoBIN office, and 10 in Kampala ready for transport. During the 2011 evaluation we compiled a list of all the BSFs and their locations, and used a portable microbiology laboratory (PML) to test water before and after filtering in cases where we visited working filters, and conducted a survey with eight filter recipients. The tests checked for E. coli and fecal coliform contamination. The tests include a 10-ml Colilert test that measures the presence/absence of E.coli and fecal coliforms and a 1-ml Petrifilm test that quantifies the number of colonies. Using the results from those two tests together, we were
able to categorize each water sample into a World Health Organization (WHO) risk level associated with drinking. Recipients reported that their filters were used in the following ways: drinking (6), cooking (3), bathing (3), boiling milk/making tea (2) and demonstration (1).
Upkeep for filters includes cleaning whenever the flow rate slows. If the water comes out dirty, the filter needs to be cleaned and the water needs to be pre-treated with moringa seeds or another method. Filters can be cleaned by simply stirring the water on top without disturbing the sand and then replacing the dirty water. This process should be continued until the water is clean. Seven out of seven recipients reported that the filter is easy to use and one of the seven mentioned that it is only easy to use if you’re
To increase sustainability and accountability VHP and CoBIN would like to get the beneficiaries involved in the construction process and possibly painting of the filter. This could instill a sense of ownership and pride in the filters. During the evaluation VHP also encountered a few damaged filters and made plans with CoBIN to have them repaired.
Technology for Tomorrow’s page on BSF: http://t4tafrica.co/filter.html