First let me say; it has become increasingly obvious that collaboration is a powerful tool for the development of technology. Just look at Android which came from Linux – the ultimate technology collaboration example. When Linux first came out, certain people laughed at it – now it is recognized world wide as the best system ever created (IMHO).
Now I would like to make some clarifications here. My filter design is covered by the Creative Commons license, which allows anyone to use and sell the design, or add to it and improve on it, with proper citations. I do not claim that the water running through my filter design is guaranteed to be potable in all cases.
With all due respect to Dr. David Manz, the filters I have built and have been testing for the past 4 years are not “Biosand” filters. They are modified slow sand filters, and so far the tests have shown that the design is functional and “cleaning” is not needed in the same fashion as other biological sand filters, as the use is different; and furthermore, the input water is roof water or well water that has very low turbidity and / or contains hydrocarbon pollution from the roofing material and local air pollution. So, please, don’t confuse my design with the “Biosand” filter. It is not the same. The only close similarity is that both types of filters use biological action.