the first stage：ppf cartridge, to remove suspended substance and other substance up to 5 micron in raw water;
the second stage：granular activated carbon cartridge;
the third stage：high density activated carbon cartridge, to remove odor、chlorine and its outgrowth in raw water．
after above three stages filtration, the filtered water is pushed into the fourth stage: the reverse osmosis (ro) membrane with high pressure pump. since the aperture of the ro membrane is only 0.0001micron, bacteria and filterable virus can pass the ro membrane only if the bacteria would be reduced 4000 times, and filterable virus would be reduced above 200 times．consequently, any super fine impurities、harmful soluble solid、bacteria and virus in water is blocked by the high density ro membrane．the ro membrane can separate other impurities and contamination from the filtered water．the harmful substance is removed from waste water outlet automatically. the water filtered through the ro membrane enters a pressure tank to store．when the user turns on the goose-neck faucet，the purified water will go through the fifth stage---postpositive bacteriostatic activated carbon filtration to flow out.
    the system controls the process of water purification automatically．when the pressure of raw water is low or the water storage tank is full，the system will stop the purification machine automatically; when the water pressure returns to a normal condition，the purification machine will rerun automatically．the water purified by the ro system is the living water without bacteria and impurity, rich of oxygen，having a delicious taste，with excellent seepage force and solution power, with the function of activating the body cell and viscera，and reinforcing immunity from disease and resistibility．