Locate a large hand-held pump sprayer to use as the applicator for the bleach solution. Grasp the top and turn it counterclockwise to unscrew it.
Fill the sprayer with a mixture of one part standard household bleach with three parts of water.
Place the top onto the sprayer and turn it clockwise until it is tight. Grasp the top handle and pump it up and down until you feel pressure, which means the sprayer is ready for use.
Spray a small portion under the deck with the bleach mixture to test for color fastness. Wait 15 minutes after applying it and then blot the area with a towel. If no color change occurs, proceed with cleaning the entire deck.