Abstract: A multi-purpose fitting system includes a container having an inner tank and an outer tank made of a plastic material. An aperture is provided at the top of the container in which a multi-purpose fitting is provided. The fitting includes a close-off fitting base having a flange which is permanently attached to an outer surface of the inner tank. A close-off skirt made of a plastics material rest on the flange and extends beyond the flange to additionally rest on the outer tank. This skirt is securely attached to an outer surface of the outer tank such as by a continuous weld which provides a seal between the skirt and outer tank. A close-off ring is threadably received on a threaded upper portion of the close-off fitting base to press the skirt against the flange. A fitting member is threadably received in an interior threaded aperture of the close-off fitting base as appropriate.