Abstract: A filtration system having an in-line filter cartidge with the inlet at one end of the filter cartridge ans the outlet at the opposite end of the cartridge. The filter cartridge is connected to the cartridge mounting on the fluid conduits via quick-disconnect couplers with built-in automatic water shutoff capability which enables the filter cartridge to be installed and removed in a horizontal movement. A recirculating bypass is provided in the system which includes a pair of bypass branch lines to recirculate the fluid and prevent trapped stagnant water in the bypass lines.