US Patent 7331070 Portable sink for the handicapped

A portable sink includes first and second storage tanks for storing clean and dirty water respectively and a concave basin between the two tanks. The sink also includes a plastic base member that supports the clean water tank above and to one side of the base and the second tank below the concave basin. A normally closed one-way depressible valve connects the basin and the second storage tank for allowing water to drain into the second tank by gravity and from preventing dirty water from being returned to the basin. The valve also includes a circular plug with an upwardly extending skirt and a coil spring within the skirt for biasing the valve into a closed position.