The short answer is nothing. There are EPA regulations that prohibit the use of chemicals, soaps, oils, even waste water near or on protected waters which most lakes and other large bodies of water are. Check with your local EPA for what you can and cannot do in your area. *If you can use source water, then check out Dirt Killer classics or Kranzle machines. They are self priming and can draw water from whatever body of what you are working on or near.