I wash our MH with no pressurized water. We do have very hard water. My method is filling a 5 gallon pail with 4 gallons of water, less than 1/8 cup of cider vinegar and a couple drops of dawn dish soap. By using a squeegee combo sponge all on the same head, it attaches to a painters extending pole. I soak the sponge part in the water and do sections at a time. Before it has a chance to dry I squeegee it off. Never have any spots. I can do the whole coach with water leftover.
I even do it at campgrounds.
