As technology advances and community needs vary, the quest for the appropriate technological solution is ongoing. The solutions used in Haiti and Honduras serve as excellent examples of Pure Water’s diligence in this regard.
Among the factors we consider when choosing the right solution:
Cost: Beneficiaries in rural or underserved developing countries cannot afford expensive techniques.
Reliability: The purification system must operate for years with little maintenance.
Power: The ideal system will not be dependent on external power or sunlight.
Location: Extensive field experience has determined that locating point-of-use water purification technology in homes, schools, orphanages, and health clinics produces the most effective results.
Simplicity: Education and follow-up monitoring by trained personnel are essential to success. The simpler the system, the better the outcome.
Quantity and Quality: The equipment must consistently produce enough safe water to meet daily needs of children and their families.
Supply Chain: The ideal system cannot be dependent on the availability of parts that aren’t available locally.
Satisfying all of these requirements has led Pure Water to advocate slow sand filtration as the preferred methodology in most locations. Slow sand filtration has been in widespread use in large and small communities in Europe and America for centuries. This technology is ideally suited to the requirements of populations in developing countries.
The intermittent slow sand filter was developed by Dr. David Manz of the University of Calgary, Alberta. It was extensively tested in laboratories at the University of Calgary, MIT, and Dartmouth College, and proven economical and effective in thousands of field installations. In its residential-sized format, it is about the size of an office water cooler, constructed of either concrete or plastic with plastic piping, and filled with multiple grades of sand and gravel.
How it Works
The users reduce contaminants by pouring surface or ground water through the filter to obtain water that is safe for drinking, food preparation, personal hygiene and sanitation. The removal of harmful contaminants and pathogens takes place in the top two inches of the sand below the water surface. A natural bio-layer of microorganisms present in the contaminated water forms at this interface, which actively consumes further organic material from the water that then filters through the sand layer. The resulting water flowing from the outlet pipe is free of contaminants, clear in color, clean in taste and smell, and safe for human consumption.
Many published technical reports attest to the effectiveness of intermittent slow sand filtration. These reports confirm that under optimal operating conditions, the biosand filter is capable of removing 97% of fecal coliform, 100% of giardia cysts, 99.98% cyptosporidium oocysts, 100% of worms, 100% of parasites, and up to 90% of organic and inorganic toxicants from contaminated water and reducing diarrhea by 47%.
The biosand filter is a low cost and simple, sustainable solution that makes a measurable difference in the lives of children and their families.
