An adapter is provided for fluidly coupling a hose to a housing of a filter assembly having a drain body connected to the housing. The adapter has a retaining cap that is disposed about a central axis and is configured to couple with the drain body. A hose barb body is disposed rotatably about the central axis. The hose barb body has a tapered portion that is configured to receive at least a portion of the drain body therein, and a cylindrical portion that extends from the tapered portion. The cylindrical portion is configured to allow selective coupling of a hose thereon. A retaining collar is disposed about the central axis and has a shoulder that is configured to bear the hose barb body thereon. Multiple resilient tabs upstanding from the shoulder have ends laterally extending away from the central axis for engaging with the retaining cap.