Reader blog question #2

Hmm. It appears that nobody has answered our reader contest: blog question #2. We will change the rules from the fifth person to correctly answer to the first person to correctly answer. Scoll down through the entries of this blog to find the on about the blog question #2 to see the original question. You can find the answer on the RDI’s website at

Prof Leonard De Rooy


2 thoughts on “Reader blog question #2

  1. When we lived in Nigeria a generation ago, we had ceramic filters to filter our drinking water. Because we had access to fuel, we would first boil our water, cool it and then pour it into a large container holding two ceramic cylinders that had been attached to the bottom of the container somehow. This container was placed on top of another container that had a spigot for us to access the purified water. The ceramic filters were able to filter out protozoa, bacteria and other things that made our water dangerous to drink and change the water into much appreciated drinking, cooking and brushing teeth water. From reading the information at, I now know that the filters were also coated with silver – inside and out. This has been found effective in “inactivating” bacteria and viruses. I have also now learned that the clay was mixed with rice hulls or some other combustible material to create pockets within the filters that would allow a faster filtering rate than if the filters had just been made of clay. One memory I have of using our clay filters is that every week or so, we would have to clean off the “sludge” from the outside of our filters to help them be better filters again.

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