An automatic cleaning assembly having an outer body and an inner lid which, when attached to each other, may define an inner chamber and an outer chamber. Refill water may enter the inner chamber through a fluid flow path of an inlet. A cleaning agent disposed within the inner chamber may be partially dissolved upon contact with the water. The water with the dissolved cleaning agent begins to fill the outer chamber and exit out of the outlet of the automatic cleaning assembly. The outlet of the automatic cleaning assembly is positioned above the inlet of the automatic cleaning assembly such that water is retained within the outer chamber to prevent gas caused by the cleaning agent from escaping into the environment. Moreover, the automatic cleaning assembly may have a check valve to prevent water from back flowing into a ball cock of the toilet.