I've been curious whether a home RO (Reverse Osmosis) filtration system would filter microcystin. I found two references, both saying it depends on the pore size and contamination level. These sources also mention other purification techniques. PDF warning for both references:<p><a href="http://www.who.int/water_sanitation_health/dwq/chemicals/microcystin_sections.pdf" rel="nofollow">http://www.who.int/water_sanitation_health/dwq/chemicals/mic...</a><p>> Dissolved microcystins have been shown to be removed by some reverse osmosis
and nanofiltration membranes. As removal will depend of membrane pore size
distribution and water quality, site specific tests are recommended<p><a href="http://water.epa.gov/scitech/swguidance/standards/criteria/nutrients/upload/cyanobacteria_factsheet.pdf" rel="nofollow">http://water.epa.gov/scitech/swguidance/standards/criteria/n...</a><p>> Nanofiltration and reverse osmosis are effective in removing cylindrospermopsin and microcystin. However, site specific tests are recommended as removal efficiency depends on the membrane pore size distribution and water quality.