Abstract: An assembly for collecting and disposing of waste solvents in a manner to meet safety requirements of municipalities. The assembly includes a waste tank and an open-top container for receiving and supporting the waste tank. The container has a greater internal volume that does the waste tank so that, when the waste tank is in the container, a space surrounds the waste tank. Such space is adapted to receive and trap any leakage or overflow of the solvent from the waste tank during use of the assembly. The waste tank has a first port for receiving waste solvent and a second port for allowing the waste solvent to be pumped out of the waste tank. Liquid level sensors are provided on the waste tank for sensing the solvent therein at different levels. The container has brackets for positioning the waste tank on the bottom of the container, and the container has casters to allow the assembly to be easily shifted from place to place.