6th April 2012 at 1:51 pm #781
Quite right about the differences between activated carbon and charcoal – activated carbon is much more effective. In fact we don’t really know the effectiveness of adding charcoal at all. It would therefore be interesting to have someone do some research into filters with and without a charcoal layer.
However, I think we should keep in mind that most raw water would be adequately treated by aeration and filtration alone – for example some bad taste and odour is easily removed by adding oxygen and waiting a while, and taste coming from organic matter may reduce when this is degraded within the filter bed. I guess that is why so far there has been no charcoal in any of the official CAWST or biosandfilter.org designs.