Crystal Quest Reverse Osmosis membranes remove 99.9% of contaminants and unwanted particles sizes as small as 1/1000 of a micron. They do this by forcing untreated water through a semi-permeable membrane. The pressure forces the water in the reverse direct to the flow in normal osmosis. Some contaminants removed are lead, sodium, cyanide, ammonium, mercury, bromide, cadmium, trivalent chromium, radium, magnesium, fluoride, nitrates and many more.