WATER TREATMENT BY BIOSAND FILTERS

The World Health Organization has determined that 1.1 billion people worldwide lack access to a potable water supply; and that 1.8 million people die every year from diarrheal diseases. The WHO estimates that 94% of these deaths could be prevented by improved water supply and storage and improved sanitation and hygiene practices.

Community drinking water sources in the high Andes, especially where drawn from surface sources, are frequently contaminated by fecal coliform bacteria, parasites and other pathogens. The community health consequences of water-borne contaminants are very high rates of under-five, elderly, and maternal disease and mortality. For most high Andean communities, treatment of drinking water and enhancement of hygiene and sanitation practices are the most important measures which can be taken to improve public health.

Since early 2008, DESEA Perú has been constructing “biosand” water filters in homes and schools in high Andean communities near the Sacred Valley (Cusco region). These filters – designed in 1988 by Dr. David Manz at the University of Calgary - have been further developed and promoted by the Centre for Affordable Water and Sanitation Technology. By its extension work, CAWST has fostered adoption of this technology at locations throughout Africa, Asia, and the Latin American-Caribbean region.

The biosand water filter system involves filtering of water within a one-metre tall, free-standing concrete container of sand, a biologically-active layer at the sand surface, and lower, drainage layers of gravel. A household filter can provide up to 20-40 litres/hour. Based on in-house and independent studies, CAWST reports that biosand filters are able to remove 95-99% of bacteria; 80-90% of viruses; and 99.99% of parasites (including Giardia, Cryptosporidium, other protozoa, and helminths).

In the DESEA project area, the biosand water filters are constructed in small, community-based workshops by trained local staff with the assistance of families who are to receive filters. Following installation in homes, families receive on-going support from DESEA staff regarding water filter operation, hygiene and sanitation practices, and family health. At the same time, water filters are closely monitored to assure that they are correctly managed and are providing optimal water treatment.

Continuous family and community contact is a vital element of DESEA’s approach; acquainting community residents with the link of water quality to human health and with the need to adjust hygiene and sanitation practices is normally a very gradual process. Through the long term, DESEA’s community health workers will provide this day-to-day support, while maintaining contact with DESEA staff and other government and non-government medical services.

____________________________________________________________________________________