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WaterAid partner pilots BioSand filters

Constructing a BioSand filter
Constructing a BioSand filter.
Credit: WaterAid

By Umar Nuhu, Afram Plains Development Organisation (APDO)

WaterAid partner APDO is using BioSand filters to ensure hard to reach communities gain access to clean water.

The BioSand filter is a low cost water purifying technology made of cement that uses different soil aggregates to filter water for households. This technology, of which many of the materials can be sourced locally, has the ability to remove 99% bacteria and viruses. The technology is able to filter 40 litres of water per hour which can meet the daily drinking water requirements for many households.

The low water table and the inaccessibility of areas along the Volta Lake in the Afram Plains has made it hard for communities living there to gain access to potable water as it is virtually impossible to get drilling rigs to the communities.

In 2001, WaterAid contracted the British Geological Survey (BGS)  to conduct research into the soil along Ekye - Agyata road to determine alternatives for future drilling exercises. They recommended drilling deep wells but, despite success in some communities, the difficulties still persisted in others. These communities continue to rely on the Volta Lake and rivers as their main sources of water supply.
 
To address this problem, APDO organised a workshop on  construction of BioSand filters in collaboration with the Center for Affordable Water and Sanitation Technology (CAWST) of Canada. Participants were drawn from APDO staff, selected artisans from the communities and staff from New Energy, Rural Aid, ProNet North and Ghana Prison Service. CAWST has been spearheading the promotion of this technology in low income countries worldwide.

APDO has started promoting this technology in four lakeside communities as a pilot project. Should the pilot succeed, the initiative could serve as a breakthrough for providing many more people with access to potable water throughout Ghana.

The technology

The BioSand filter is a low cost water technology made of cement and uses different soil aggregates to filter household water. A bag of cement can be used to construct three BioSand filters. The other materials, fine sand and gravel, can be obtained locally. This technology has the ability to remove 99% bacteria and viruses but not chemical pollutants. The technology is able to filter 40 litres of water per hour which can meet the daily drinking water requirements for many households.

Operation and maintenance
The BioSand filter is a ‘point of use’ or household treatment device. The water to be filtered can be obtained from the closest water supply point, whether river, stream or well, carried to the filter, and used immediately after filtering.
 
The operation and maintenance of the filter is simple. The design of the outlet system ensures that a minimum water depth of five centimetres (5cm) is maintained over the sand when the filter is not in use. This makes the filtration processes effective.

When the flow through the filter becomes too slow, the maintenance consists simply of washing the top few centimetres of sand. The operation and maintenance of the filter are therefore well within the capacity of the entire household, including children.

The filter takes up very little space and can easily fit into most rooms. The cost of operating the filter is negligible. There are no consumables involved in the filtration process. There are no moving parts which require replacement on an ongoing basis. Maintenance costs may include the occasional replacement of iron nails (for arsenic removal) and any wooden components (for example, the lid) that may deteriorate over time. Consequently, once installed, the filter can be used almost indefinitely.