The lake water ,steam water ,rain water after filtering of PP cotton pre-filter  ,can filter thr sand ,rust and the other large particles.The water comes into the carbon fiber filter after coarse filtration,this class can filter the micro-mud ,vermin ,peculiar smell ,heavy metal and other harmful substances. At last the water enters into ultrafiltration membrane filter,it can filter evey kind of pathogenic bacteria and the other microorganism to make the water be safe drinking water.