A coupling assembly includes: a tubular compression collar having a tubular body made of a resiliently flexible polymeric material and having an interior surface and an opposing exterior surface; an end of a tube disposed within a throughway of the compression collar; and a tube fitting disposed within the passageway of the tube. The tube fitting includes: a tubular stem; a flange radially outwardly projecting from an exterior surface of the stem; and an annular barb encircling and radially outwardly projecting from the exterior surface of the stem, the annular barb including a frustoconical outside face that extends along and outwardly slopes away from the stem as the outside face extends toward the flange. The compression collar radially inwardly compresses the tube against the annular barb of the tube fitting so that a liquid tight seal is formed between the tube and the tube fitting.