Like Korkie Said. One is for fresh water from the slip. This is the one that does not look like a normal hose fitting you would attach at garden hose to. The other is for your fresh water washdown, it allows you to wash your boat when you are not connected to fresh water from the slip. You could use this for anything, including what Estero said, flushing your engine, although that would normally be done while you have shore water?
