A real barrel of laughs he was, indeed.
found this :
SMALL-SCALE DRINKING WATER PURIFIERS IN THE REMOVAL OF CYANOBACTERIAL TOXINS
Erkki Vuori assoc.prof.
Department of Forensic Medicine, University of Helsinki
The ability of small-scale drinking water purifiers to remove toxins produced by cyanobacteria was studied by contaminating natural waters with neurotoxic Anabaena flos-aquae and hepatotoxic Microcystis aeruginosa or hepatotoxic Nodularia spumigena.
Before each purification experiment, a volume was separated from the contaminated water samples and toxin concentrations of the treated water samples were then compared with concentrations of untreated volumes. The reduction percentages were used to evaluate the efficiency of each purifier.
Water treatment procedures based on filtration (Katadyn R and Stella Meta R) did not remove anatoxin-a and these methods were thus rejected from further experiments.
If granulated activated carbon is included in the treatment procedure (Berkefeld Filter R), removal is possible but the behaviour is unpredictable.
Of all the methods tested reverse osmosis (Freshwater R) was the only method capable of reliably removing anatoxin-a and microcystin.
Simulated vacuum distillation purification experiment with brackish water showed that nodularin did not penetrate the distillate. The use of ineffective drinking water purifiers involves an extra risk since all the purifiers tested could produce clear and suitable water from green and apparently non-potable raw water.”
http://www.nessling.fi/symposiot/Symposio1/vuori.htm