Encapsulated filter cartridge

An encapsulated filter cartridge for filtering fluids, comprising:

• a filter assembly having an upper end, a lower end, an axial portion and a radially outer surface and including:
• a carbon block filter element;
• and
• a gradient porosity microporous filter element surrounding the carbon block filter element, the microporous filter element being operably positioned upstream of the carbon block filter element and being effective to substantially retain microorganisms before the microorganisms can enter the carbon block element such that the microorganisms are substantially prevented from growing, multiplying and eventually colonizing the filter cartridge, the gradient porosity microporous filter element comprising:
• a membrane structure having a thickness of between about 130 and about 300 microns and a plurality of adjacent discrete zones, wherein any downstream zone has an average pore size from about 0.05 micron to about 0.8 micron;
• a permanently sealed sump defining an interior chamber configured to accommodate the filter assembly, the sump having an inlet for permitting unfiltered fluid to enter the interior chamber for communicating with the radially outer surface of the filter assembly, and an outlet for permitting filtered fluid to exit the interior chamber from the axial portion of the filter assembly;
• and
• structure for selectively connecting the encapsulated filter cartridge to a fluid source and selectively disconnecting the encapsulated filter cartridge from the fluid source.