A portable sink assembly for includes a cube that is positionable in a sleeper of a semi tractor be accessible to a driver. A sink is recessed into the cube to contain water and a faucet is removably coupled to the cube. The faucet is directed into the sink to direct the water into the sink. A pump is positioned in the cube, the pump is fluidly coupled between a water source and the faucet for pumping the water to the faucet. A valve is coupled to the pump and the valve is actuatable between a minimum flow rate and a maximum flow rate. In this way the valve adjusts the volume of water delivered to the pump between a minimum amount and a maximum amount thereby facilitating the flow rate of the faucet to be adjusted.