A containment assembly for use with a pressure washing apparatus to contain and collect the relatively light weight contaminants from run-off of a washing fluid after being flowed over an object to be cleaned. The containment assembly includes a settling compartment for collection of the run-off washing fluid therein, and a containment compartment in gravity flow fluid communication with a surface of the collected washing fluid in the settling compartment. As the lightweight contaminants at the surface of the washing fluids gravity flow into the containment compartment, they are contained and collected therein. A fluid extraction assembly is in fluid communication with the contained washing fluid in the containment compartment through an opening therein vertically disposed below a predetermined operational fluid level of the contained washing fluid. The extraction assembly is adapted to extraction the contained washing fluid through the opening in a manner maintaining the gravity flow of the collected washing fluid into the containment compartment.