A submersible water separation membrane module comprising: a plurality of water separation membrane cartridges having: i) a water separation membrane, ii) an impermeable cartridge wall surrounding the membrane, iii) a first cartridge end sealed to the wall and through which pressurized salinated water flows into the cartridge and is separated by the membrane into concentrate or brine and at least partially desalinated water, iv) a second cartridge end from which the concentrate or brine exits the cartridge, and v) a product water collection tube that collects from inside the cartridge the at least partially desalinated product water passing through the membrane, and through which the at least partially desalinated water exits the cartridge; a generally parallel array of the cartridges being mounted in a perforated divider plate whose perforations surround the cartridge walls or the first or second cartridge ends, the divider plate separating salinated water flowing into the first cartridge ends from concentrate or brine exiting the cartridges; and a product water collection manifold in fluid engagement with a plurality of the product water collection tubes and into which the at least partially desalinated water flows; wherein a) the manifold is adhesively bonded to a plurality of the collection tubes, or b) the divider plate is adhesively bonded to a plurality of the cartridge walls or ends, or both a) and b). a plurality of water separation membrane cartridges having: i) a water separation membrane, ii) an impermeable cartridge wall surrounding the membrane, iii) a first cartridge end sealed to the wall and through which pressurized salinated water flows into the cartridge and is separated by the membrane into concentrate or brine and at least partially desalinated water, iv) a second cartridge end from which the concentrate or brine exits the cartridge, and v) a product water collection tube that collects from inside the cartridge the at least partially desalinated product water passing through the membrane, and through which the at least partially desalinated water exits the cartridge; i) a water separation membrane, ii) an impermeable cartridge wall surrounding the membrane, iii) a first cartridge end sealed to the wall and through which pressurized salinated water flows into the cartridge and is separated by the membrane into concentrate or brine and at least partially desalinated water, iv) a second cartridge end from which the concentrate or brine exits the cartridge, and v) a product water collection tube that collects from inside the cartridge the at least partially desalinated product water passing through the membrane, and through which the at least partially desalinated water exits the cartridge; a generally parallel array of the cartridges being mounted in a perforated divider plate whose perforations surround the cartridge walls or the first or second cartridge ends, the divider plate separating salinated water flowing into the first cartridge ends from concentrate or brine exiting the cartridges; and a product water collection manifold in fluid engagement with a plurality of the product water collection tubes and into which the at least partially desalinated water flows;