SAFE DRINKING WATER

Water and sanitation services are scarce in developing countries where 11% of people do not have access to improved drinking water (UN/WHO, 2012). According to Bartram, approximately, 2.4 million deaths could be prevented annually if people practiced good hygiene and had reliable sanitation and drinking water (Bartram, 2010). 

In this blog, I would like to discuss a second WASH intervention: Biosand filters.

Biosand filters are a type of technology that households have used to remove pathogens from drinking and cooking water for over 200 years. This technique permits improvements in water quality with a reduced cost and low environmental impact and therefore, produces a high reduction of diarrheal diseases.

Source: CAWST - The Centre for Affordable Water and Sanitation Technology (www.cawst.org)

This intervention consists simply of pouring water into a biosand filter (layers of specially selected prepared sand and gravel) of about 1m tall, 0.3m wide on each side that is allocated in a container made of concrete or plastic.  The sand helps to remove pathogens and suspended solids from contaminated drinking water through a biological community of bacteria and other micro-organisms called a biolayer that eats many of the pathogens in the water.

CAWST - The Centre for Affordable Water and Sanitation Technology (www.cawst.org)

In order to measure the efficiency of this intervention in removing pathogens, turbidity and iron, the following table summarizes the effects:

	Bacteria	Viruses	Protozoa	Turbidity	Iron
Laboratory	Up to 96.5% (BUZUNIS 1995; Baumgartner 2006)	70 to >99% (Stauber et al. 2006)	>99.9% (Palmateer et al.1997)	95% (BUZUNIS 1995);	Not available
Field	87.9 to98.5% (Earwaker 2006; Duke & Baker 2005)	Not available	Not available	85% (Duke & Baker 2005)	90-95% (NGAI et al. 2004)

Health impact studies estimate a 30 to 47% reduction in diarrhoea among all age groups, including children under the age of five, an     especially vulnerable population group. 

Source: SOBSEY (2007); STAUBER et al. (2007)

As you can observe, there are many benefits of using biosand filters mainly in developing countries. The total cost of biosand filter interventions consist of the purchase of filters (sometimes subsidized in part by the local or national authorities) and training activities on the maintenance of filters (Whittington, 2012, p.1158).  According to the study Impact of BiosandFilter on Access to Safe Drinking Water in the Rural Communities of thePhilippines, the annual total economic benefit of households who use biosand filters was US$814.92 with a benefit-cost ratio at 12.48.

How can we spread these benefits to those countries that are still not using this intervention?