Biosand Water Filter: Reducing Water Borne Illnesses


SEATTLE — Each year, four billion cases of diarrhea are associated with a lack of access to safe drinking water. Similarly, the U.N. estimates that nearly 900 million people receive their water from an unimproved source. One response to this issue is the Biosand water filter system.

Since professor David Manz of the University of Calgary pioneered the system, it has significantly reduced the leading causes of waterborne disease and death in the developing world. The Biosand water filter is composed of either a plastic or concrete container that holds sand and gravel to naturally produce clean drinking water.

The systems are specifically designed for household use and do not require electricity. Users simply pour surface or ground water through the filter, causing harmful organisms to naturally die off, and they can obtain water safe for drinking, personal hygiene and sanitation. The system can meet the needs of three or four families.

A typical Biosand water filter can produce between 20 and 23 liters every hour. The system costs about $100 for a complete installation according to Samaritan’s Purse, an NGO which has installed more than 120,000 Biosand filters in 24 countries.

Health impact studies on the filtration system have proven it to be effective, reliable and affordable. For example, in a study in Nepal, researchers at MIT found 99.5 percent removal of total coliform bacteria. Laboratory studies at the University of North Carolina indicated about 99 percent reduction of E. coli.

Similarly, studies in a Canadian lab report showed evidence of a 99.9 percent removal of protozoan parasites. The system’s effectiveness was recorded in the 2007 Health Impact Study in Cambodia, showing a 95 percent reduction of E. coli and 44 percent reduction in diarrhea.

According to professor Mark Sobsey of the University of North Carolina, Hydraid BioSand Filter technology is the best overall technology for the developing world. The Hydraid filtration system is unique in that it uses a lightweight plastic vessel rather than a concrete one. The plastic system is also more sustainable, produces more water, treats a greater range of water qualities, is easier to operate and less expensive than its concrete counterpart.

According to the World Health Organization (WHO) in 2008, reducing diarrhea and malnutrition from unsafe water could prevent the deaths of 2.2 million children every year. Biosand water filters have already reached more than 70 countries across Africa, Europe, Asia, North, Central and South America, the Caribbean and the South Pacific. Overall, the success of the Biosand water filter represents a huge step in granting people of the developing world access to clean drinking water.

Liliana Rehorn

Photo: Flickr


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