Patent ID: 7449117

Claim:
A filtration unit comprising: a casing having an elongated shape with a height being greater than a width and has a bottom, said casing for being disposed in a water storage tank into which raw water is introduced, at least one introduction port provided in a side of said casing that introduces raw water contained in said water storage tank into said casing, said introduction port being a only entrance for raw water into said casing, an active carbon supply means that supplies active carbon into said casing to be added to the raw water introduced into said casing, an agitation means that agitates the raw water which is inside said casing and to which the active carbon has been added, a filtration module provided in said casing that filters the raw water, a back flow prevention means that prevents the raw water inside said casing from flowing back through said introduction port and being discharged into said water storage tank, and a discharge means that discharges filtered water from said filtration module in said casing; and wherein said at least one introduction port is disposed so as to open in a water surface of the raw water inside said water storage tank, and a partition plate that restricts inflow of the raw water at said water surface is provided at least around said introduction port on an outer circumference of said casing, said partition plate extending above and below said water surface such that matter floating on said water surface of said raw water are prevent from entering said casing via said introduction port.