Passive membrane filtration system with pre-treatment

A multiple filtration cartridge assembly designed to fit within a structure, the assembly comprising:

• one or more hollow collection rail(s) with one or more opening(s), with at least one opening for flow out of the rail on an end of said rail, and at least one opening for flow into the rail located on the top of said rail,
• wherein said collection rail(s) are designed to be positioned horizontal in a bottom portion of the structure,
• wherein said openings of said collection rail(s) are coupled to one or more solid internal riser tube(s) with open tops to allow water to flow into the center of said internal riser tube(s) and transfer water into the collection rail(s),
• said internal riser tube(s) are coupled to allow one or more filter cartridge(s) to be placed surrounding the internal riser tube(s), with said filter cartridges comprised of a perforated inner cartridge housing, and an outer filter media,
• wherein, said filter cartridge(s) are taller than said riser tube(s), and as such are installed enclosing the area around said riser tube(s) in contact with said collection rail(s) and forming a water-tight seal with the horizontal collection rail(s), wherein said one or more riser tube(s) extend up into the one or more filter cartridge(s) such that water passing through said filter cartridge(s) media must travel from the inside of the perforated inner cartridge housing(s) and up to the top of the internal riser tube(s) and back down to the collection rail(s),
• said collection rail(s) extending to an outlet portion with an open end to allow water treated by said filter cartridge(s) to exit said collection rail(s),
• wherein the internal riser tubes and filter cartridges are mounted on the collection rail with two or more rail couplers and wherein one of the riser tubes contain a drain down orifice.