The present invention relates to a filtering device, which comprises a base plate (12) having a threaded center hole (122); a filter housing (11) having a cap-shaped body coupleable to the base plate; an anti-drainback valve (15) having a valve hole (151) defined in the center portion thereof arranged on the base plate (12), where the valve hole (151) correspondingly aligns with the threaded center hole (122) of the base plate (12); a filter assembly (14) having a filter hole (1411) abutting on the anti-drainback valve (15), where the filter hole (1411) aligns with the valve hole (151) of the anti-drainback valve (15); and a bypass valve (13) having a central plate portion (132) and a pair of extending wing portions (131) pressingly arranged between the inner surface of the filter housing and the filter assembly. The separately removable housing (11) provides easy assembly and enables simple filter media replacement.