If you have a small farm with lots of produce to wash you might want to build this gap (Good Agricultural Practices) approved barrel sink to wash the produce in. This helps to ensure that pathogens are not transported on the produce. It can be part of a whole system including a sink for hand washing, the sink for washing the produce and drying racks. The entire system is called The Leopold Model. A lot of produce buyers now require vendors to be GAP certified. This is also a good washing system for farmers that sell at farmers markets. Hobby Farms shares the tutorial for building the sink and provide the link to a pdf to build the whole Leopold model.
Click here for instructions>> http://www.hobbyfarms.com/farm-marketing-and-management/build-gap-approved-barrel-sink.aspx