least 90 u00b0 more preferable is a cartridge design that maintains filter immersion from the vertical through a tilt angle of at least 150 u00b0 in at least one tilt direction in some cases as where priming of the cartridge is carried out as part of the manufacturing process the cartridge will be shipped and stored in a pre primed condition since in these cases the cartridge may assume any orientation the cartridge will typically be provided with temporary seals applied to the inlet and outlet ports to prevent air access to the micro porous filter element the path of water flow through the cartridge is not critical to the invention the flow path may be convoluted or direct and include flow path segments directed upwardly against gravity laterally downwardly or in various combinations thereof further the cartridge housing may in addition to raw water inlet and treated water outlet openings include such features as a main filtration chamber various water transfer passages air vents water valves and or tubing these will be designed to control water flow within the cartridge and most importantly to prevent exposure of the micro porous filtration medium to air in both the upright and tilted cartridge orientations fig1 a 1d present schematic elevational cross.