BioSand Water Filtration Systems

The water tanks previously mentioned on this website function as rain catchment systems, collecting water from the rooftops of adjacent homesteads and storing them for year-round use. Although Uganda is known in East Africa for its green landscape and two wet seasons, there is also a dry season when many of the current sources of drinking water dry up partially or completely. During this time, people would ideally have water saved in their tanks to sustain them through the dry season. Although we acquired the means to build and maintain two more water tanks than the original two planned for the region, by selling AIDS pins on the UW-Madison campus made by workers at REACH-OUT, there are still nowhere near enough tanks for each family in the area to benefit. These families are drinking water from stagnant pools year-round while the families with tanks are drinking contaminated water during prolonged dry seasons after the clean water in their tanks is consumed.

BioSand Water Filters provide an opportunity to improve the quality of current water sources. Dr. David Manz, a Canadian engineer, designed them specifically for intermittent use, allowing the concrete filters to be built on-site at a scale suitable for individual households. Water passes through sand and gravel layers and then comes out of the filter at a rate of 1L/minute. There is always a small amount of water that does not drain from the filter, and this standing water develops a slime on top, which forms a biological layer filled with aerobic bacteria that eat the bad bacteria. 90% of the bacteria are removed as water flows through this top biological layer, and then the sand filters out 100% of the parasites and larger organisms.

It is our hope that the BioSand Water Filters, paired with the rainwater collection tanks, will be an efficient and economical way to provide clean water year round to rural Ugandan communities. 

This project is currently being funded through the Wisconsin Idea Fellowship, provided by the Morgridge Center for Public Service.

UPDATE: Our filter project has officially been started! Below is a picture of the filter mold built by engineer Paul Kimera in Uganda. This mold will be used to pour the concrete casing for all the filters.

Below is the first completed filter.  Paul Kimera (right) and his construction team are currently testing this filter for effectiveness and purity.

Below is a picture of water before & after it was poured through a BioSand water filter. The water on the right is before filtering, and the water on the left is after filtering.