Clean the washboard with mild soap and water using a sponge. Wipe down the ridges on the front and back of the board to remove any dirt or residue. Wash out the bucket and let everything dry thoroughly.
Attach the plastic tubing to the outlet port on the pump by pushing the tube fully onto the outlet nozzle as far as it will go. Place the pump in the empty plastic tub.
Stand the washboard up behind the tub while holding up the plastic tubing. Note the height of the washboard against the tubing, and mark the tubing six inches taller than the washboard with a permanent marker. Set the washboard aside. Cut the tubing along the mark using scissors or a craft knife.
Fill the plastic tub with water while the pump is in place.
Hold the end of the plastic tubing straight up and turn the pump on. Adjust the pump's output control so the water squirts out the top of the tubing at a desirable rate. Turn the pump off.
Set the plastic water-filled tub into the old metal bucket or wash tub. Position the washboard inside the plastic tub behind the pump. The washboard should sit vertically or at a slight angle with the top leaning backward so running water will return to the tub. Position heavy stones or bricks at the bottom of the washboard to keep the washboard in place, if necessary. The rocks may not be needed if the pump weight secures the washboard well.
Run the tubing up the back of the washboard. Position the top of the tube so it will spill pumped water down the front of the washboard. Turn the pump on to test for ideal tube placement.
Secure the tubing to a leg of the washboard with one or more plastic zip ties, depending on the height of the washboard. Although one zip tie will do the trick, using more allows you to hide the tubing behind the washboard leg.