In accordance with at least selected embodiments of the present invention, an improved liquid degassing membrane contactor or module includes a high pressure housing and at least one degassing cartridge therein. It may be preferred that the high pressure housing is a standard, ASME certified, reverse osmosis (RO) or water purification pressure housing or vessel (made of, for example, polypropylene, polycarbonate, stainless steel, corrosion resistant filament wound fiberglass reinforced epoxy tubing, with pressure ratings of for example, 150, 250, 300, 400, or 600 psi, and with, for example 4 or 6 ports, and an end cap at each end) and that the degassing cartridge is a self-contained, hollow-fiber membrane cartridge adapted to fit in the RO high pressure housing.