Patent ID: 6991737

Claim:
A filtering method comprising; providing a water purifying apparatus comprising a cell structure and a cap portion, the cell structure being configured to combine, in a direction perpendicular to cells, one or more units constituting cell structure, each having a plurality of cells being defined by partition walls made of a porous body to be flow channels of raw water, the cap portion being arranged with a predetermined space formed at one other end lest the raw water flowing into the cells from one end of the cell structure should pass through the cells and flow to the outside from the other end, the raw water being made to flow into the cells from the one end of the cell structure of the water purifying apparatus, flowing raw water from one end of said cell structure to make raw water flowed into the cells permeate through the partition walls to remove foreign substances contained in raw water with the partition walls to filter raw water, and, taking out a filtered raw water as a filtered water from the side of an outer peripheral surface of the cell structure, wherein the partition walls of the cell structure are so constructed that a ratio of water permeability between partition walls showing a maximum water permeability and partition walls showing a minimum water permeability among the partition walls is within a range of from 110 to 300% in terms of percentage, and wherein cells located on the outer periphery of the cell structure have a greater water permeability, whereby raw water flowed into the predetermined space of the cap portion from the cells with a smaller water permeability is made to flow conversely from the end facing the cap portion in the cells with a greater water permeability of the cell structure, and the raw water flowing conversely is made to permeate the partition wall to be filtered, and thereafter the filtered raw water is taken out as the filtrate water from the side of the outer peripheral surface of the cell structure.